Polyene compounds

ABSTRACT

Novel 9-substituted or unsubstituted thienyl-3,7-dimethyl-nona-2,4,6,8-tetraene derivatives, useful as antitumor agents as well as processes for their preparation and novel intermediates are disclosed.

RELATED APPLICATIONS

This is a division of application Ser. No. 801,688, filed May 31, 1977,now U.S. Pat. No. 4,116,975, which in turn is a division of applicationSer. No. 733,507, filed Oct. 18, 1976, now U.S. Pat. No. 4,061,656,which in turn is a continuation-in-part of U.S. patent application Ser.No. 632,029, filed Nov. 14, 1975, now abandoned.

SUMMARY OF THE INVENTION

In accordance with this invention, it has been discovered that compoundsrepresented by the formula ##STR1## wherein one of R₁ or R₂ is ##STR2##and the other of R₁ or R₂ and R₃ and R₄ are hydrogen, lower alkyl thio,lower alkoxy-lower alkyl, hydroxy methyl, halogen, lower alkyl, loweralkoxy, amino, carboxyl, mono(lower alkyl)amino, di(lower alkyl)amino,mono(lower alkyl) amino lower alkyl, di(lower alkyl)amino lower alkyl,hydroxy, lower alkenyl, lower alkenoxy, lower alkanoyl, loweralkanoyloxy, nitro, lower alkoxycarbonyl, lower alkanoylamido or anitrogen containing heterocycle; and R₅ is formyl, hydroxymethyl,alkoxymethyl, alkanoyloxymethyl, carboxyl, alkoxycarbonyl,alkenoxycarbonyl, alkynoxycarbonyl, carbamoyl, mono(loweralkyl)carbamoyl, di(lower alkyl)carbamoyl, N-heterocyclylcarbonyl andaroyloxymethyl,

and salts thereof are useful as antitumor agents.

DESCRIPTION OF THE INVENTION

The present invention pertains to compounds represented by the formula##STR3## wherein one of R₁ or R₂ is ##STR4## and the other of R₁ or R₂and R₃ and R₄ are hydrogen, lower alkyl thio, lower alkoxy-lower alkyl,hydroxy methyl, halogen, lower alkyl, lower alkoxy, amino, carboxyl,mono(lower alkyl)amino, di(lower alkyl)amino, mono(lower alkyl) aminolower alkyl, di(lower alkyl)amino lower alkyl, hydroxy, lower alkenyl,lower alkenoxy, lower alkanoyl, lower alkanoyloxy, nitro, loweralkoxycarbonyl, lower alkanoylamido or a nitrogen containingheterocycle; and R₅ is formyl, hydroxymethyl, alkoxymethyl,alkanoyloxymethyl, carboxyl, alkoxycarbonyl, alkenoxycarbonyl,alkynoxycarbonyl, carbamoyl, mono(lower alkyl)carbamoyl, di(loweralkyl)carbamoyl, N-heterocyclylcarbonyl and aroyloxymethyl,

and salts thereof.

As used herein "lower alkyl" means alkyl groups which contain up to 6carbon atoms, e.g., methyl, ethyl, propyl, isopropyl or 2-methyl-propyl,"lower alkoxy" means alkoxy groups which contain up to 6 carbon atoms,e.g., methoxy, ethoxy or isopropoxy, "halogen" includes fluorine,chlorine, bromine and iodine with bromine and chlorine preferred, "loweralkenyl" means alkenyl groups which contain up to 6 carbon atoms, e.g.,vinyl, allyl and butenyl, "lower alkenoxy" means alkenoxy groups whichcontain up to 6 carbon atoms, e.g., vinyloxy and allyloxy, "loweralkanoyloxy" means alkanoyloxy groups which contain up to 6 carbonatoms, e.g., acetoxy, propionyloxy, butyryloxy and the like.

The alkanoyl portion of the lower alkanoylamido and lower alkanoylgroups are derived from lower alkanecarboxylic acids having up to 6carbon atoms, e.g., acetic acid, propionic acid, pivalic acid, and thelike. The term "aroyloxymethyl" means aroyloxymethyl groups wherein thearoyl portion is derived from an aromatic carboxylic acid residuecontaining from 7 to 11 carbon atoms, e.g., benzoic acid, toluic acid,xylylic acid and the like, preferred are benzoyloxymethyl andtolyloxymethyl.

The terms "alkoxymethyl" and "alkoxycarbonyl" include straight-chain orbranched-chain alkoxy groups having up to 20 carbon atoms, e.g.,methoxy, ethoxy, isopropoxy or cetyloxy. Preferred, however, are thosealkoxy groups containing up to 6 carbon atoms. The said alkoxy groupscan be unsubstituted or substituted by functional groups, for example,by nitrogen-containing groups such as by substituted oralkyl-substituted amino or morpholino groups, or by a piperidyl orpyridyl group. The terms "alkenoxycarbonyl" and "alkylnoxycarbonyl"include alkenoxy and alkynoxy groups having up to 6 carbon atoms, e.g.,allyloxy or propargyloxy. The alkanoyloxy groups present in thealkanoyloxymethyl groups are derived from alkanecarboxylic acidscontaining from 1 to 20 carbon atoms, e.g., acetic acid, propionic acid,pivalic acid, palmitic acid or stearic acid, however, the preferredgroup of alkanecarboxylic acids are the lower alkanecarboxylic acidswhich contain from 1 to 6 carbon atoms. The carbamoyl group within thescope of this invention can be monosubstituted or disubstituted bystraight-chain or branched-chain lower alkyl groups, e.g., methyl, ethylor isopropyl. Examples of such substituted carbamoyl groups are themethylcarbamoyl, dimethylcarbamoyl and diethylcarbamoyl groups. Theterms "N-heterocyclyl" and "nitrogen containing heterocycle" include5-membered or 6-membered heterocyclic groups which, in addition tonitrogen, may contain a second nitrogen, oxygen or sulphur. Of theheterocyclic rings piperidino, morpholino, thiomorpholino andpyrrolidino are preferred.

Preferred compounds within the scope of formula I are represented by theformula ##STR5## wherein one of R₁ or R₂ is ##STR6## and the other of R₁or R₂ and R₃ and R₄ are hydrogen, lower alkyl or halogen and R₅ is loweralkoxycarbonyl, carboxyl or mono(lower alkyl)carbamoyl,

and salt thereof.

Examples of polyene compounds within the scope of this invention are

alltrans-3,7-dimethyl-9-(2,4,5-trimethyl-3-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester;

alltrans-3,7-dimethyl-9-(2,4,5-trimethyl-3-thienyl)-2,4,6,8-nonatetraenoicacid;

alltrans-N-ethyl-3,7-dimethyl-9-(2,4,5-trimethyl-3-thienyl)-2,4,6,8-nonatetraenamide;

alltrans-3,7-dimethyl-9-(3,4,5,-trimethyl-2-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester;

all trans-3,7-dimethyl-9-(3-methyl-2-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester;

all trans-3,7-dimethyl-9-(5-methyl-2-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester;

all trans-3,7-dimethyl-9-(2,5-dimethyl-3-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester;

alltrans-3,7-dimethyl-9-(3,4,5-tribromo-2-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester;

alltrans-3,7-dimethyl-9-(3,4-dibromo-5-methyl-2-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester;

alltrans-3,7-dimethyl-9-(2,4-dimethyl-5-chloro-3-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester;

alltrans-3,7-dimethyl-9-(2,4-dimethyl-5-methoxy-3-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester;

alltrans-3,7-dimethyl-9-(2,4-dichloro-5-methyl-3-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester;

alltrans-3,7-dimethyl-9-(2,4-diethyl-5-methyl-3-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester;

alltrans-3,7-dimethyl-9-(2,4-dimethyl-5-methoxymethyl-3-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester;

alltrans-3,7-dimethyl-9-(2,4-dimethyl-5-dimethylamino-3-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester;

all trans-3,7-dimethyl-9-(2,5-dichloro-3-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester;

alltrans-3,7-dimethyl-9-(2,5-dichloro-4-methyl-3-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester;

alltrans-3,7-dimethyl-9-(2,4-dimethyl-5-acetyl-3-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester;

alltrans-3,7-dimethyl-9[2,4-dimethyl-5-(1-methoxyethyl)-3-thienyl]-2,4,6,8-nonatetraenoicacid ethyl ester;

all trans-3,7-dimethyl-9-(5-bromo-2-thienyl)-2,4,6,8-nonatetraenoic acidethyl ester;

alltrans-3,7-dimethyl-9-(2,4,5-trimethyl-3-thienyl)-2,4,6,8-nonatetraenoic-1-ol;

2,4,6-trans-8-cis-3,7-dimethyl-9-(3,4,5-tribromo-2-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester;

all trans-3,7-dimethyl-9-(3,4-dibromo-2-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester;

alltrans-3,7-dimethyl-9-(2,4,5-trimethyl-3-thienyl)-1-methoxy-2,4,6,8-nonatetraene

alltrans-3,7-dimethyl-9-(2,4-diethoxycarbonyl-5-acetylamino-3-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester;

alltrans-3,7-dimethyl-9-(3-methyl-5-methoxy-2-thienyl)-2,4,6,8-nonatetraenoicethyl ester;

alltrans-3,7-dimethyl-9-(2,4,5-trimethyl-3-thienyl)-2,4,6,8-nonatetraen-1-al;

alltrans-3,7-dimethyl-9-(2,4,5-trimethyl-3-thienyl)-2,4,6,8-nonatetraenamide;

all trans-3,7-dimethyl-9-(2,4-dimethyl-3-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester;

alltrans-3,7-dimethyl-9-[2,4-dimethyl-5-(methylthio)-3-thienyl]-2,4,6,8-nonatetraenoicacid ethyl ester;

2,4,6-trans-8-cis-3,7-dimethyl-9-(3,4-dibromo-5-methyl-2-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester;

2,4,6-trans-8-cis-3,7-dimethyl-9-(3-thienyl)-2,4,6,8-nonatraenoic acidethyl ester;

all trans-3,7-dimethyl-9-(3-thienyl)-2,4,6,8-nonatetraenoic acid ethylester.

The polyene compounds of this invention represented by formula I arepharmacodynamically valuable. They are effective in regressing thegrowth of tumors such as papillomas.

The toxicity of the compounds of this invention is slight. For example,when alltrans-3,7-dimethyl-9-(2,4,5-trimethyl-3-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester is administered intraperitoneally to mice weighing 30g. in a daily dosage of 100 mg./kg., then no indication of ahypervitaminosis-A becomes evident after 14 days (total of 10administration days).

The first indications of hypervitaminosis-A in mice appears at a dailydosage of 200 mg./kg. after 14 days (total of 10 administration days).This manifests itself in a weight decrease and a moderate hair loss andslight flaking of the skin.

The tumor-inhibiting activity of the compounds represented by formula Iis significant. In the papilloma test, tumors induced withdimethylbenzanthracene and croton oil regress. The diameter of thepapillomas within two weeks after the intraperitoneal administration ofalltrans-3,7-dimethyl-9-(2,4,5-trimethyl-3-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester decreases by 79% at a dosage of 400 mg./kg./week and by60% at a dosage of 100 mg./kg./week.

The following Table illustrates the activity and toxicity of thecompounds of this invention.

                  TABLE                                                           ______________________________________                                               Hypervitaminosis                                                                          Papilloma Effect                                                    effective dose                                                                              Dose      ± %                                       Example  mg/kg/day     mg/kg/wk  regression                                   ______________________________________                                        3            100-200  (border-                                                                             400     -69, -79, -59                                                  line)                                                                400             200     -66, -83, -50                                                         100     -60, -57, -22                                                          50     -42, -22                                 4            200                                                              5            >200            400     -28                                                                   200     -25                                                                   100     -14                                      8            100             400     -47                                                   50       (border-                                                                             400 po  -35                                                            line)                                                   12           >200            400     -18                                      14           100             400     -64                                                   50       (border-                                                                      line)                                                   37           50              200     -69                                      51           >400            400     -58, -34                                 54   (cis    200             400     -11                                           trans)                                                                   55                           400     -7                                       57   (cis    >200            400     -17                                           trans)                                                                   57   (all    >200            400     -26                                           trans)                                                                   61           100             200     -34                                      65           50              100     -29                                      69           >200            400     -23 (toxic)                              73           200             400     -43                                      104          100             200     -39                                      ______________________________________                                    

The compounds represented by formula I can be used as medicaments in theform of pharmaceutical preparations which contain them in associationwith a compatible carrier material.

Pharmaceutical preparations for systemic administration can be prepared,for example, by adding a compound represented by formula I as the activeingredient to pharmaceutically acceptable, non-toxic, inert, solid orliquid carriers which are usual in such preparations. The pharmaceuticalpreparations can be administered topically, enterally or parenterally.Suitable preparations for enteral administration are, for example,tablets, capsules, dragees, syrups, suspension, solutions andsuppositories. Suitable pharmaceutical preparations for parenteraladministration are infusion solutions.

The dosages in which the compounds are administered can be variedaccording to the mode and route of administration and according to therequirements of the patient. For example, the compounds can beadministered in amounts of from 5 mg. to 200 mg. daily in one or moredosages. Capsules containing about 10 mg. to about 100 mg. of the activecompound are a preferred form of administration.

The pharmaceutical preparations can contain in addition to the activecompounds of this invention, pharmaceutically acceptable inert orpharmacodynamically active additives. Tablets or granules, for example,can contain a series of pharmaceutically acceptable binders, fillers,carrier materials or diluents. Liquid preparations can, for example,take the form of sterile water-miscible solutions. Capsules can containa pharmaceutically acceptable filler or thickener. Furthermore,pharmaceutically acceptable flavor-improving additives andpharmaceutically acceptable substances commonly used as preservatives,stabilizers, moisture-retainers or emulsifiers, salts for varying theosmotic pressure, buffers and other pharmaceutically acceptableadditives can also be present in the pharmaceutical preparations.

The aforementioned pharmaceutically acceptable carrier materials anddiluents are well known to the pharmaceutical compounding art and can beorganic or inorganic substances such as water, gelatin, lactose, starch,magnesium stearate, talc, gum arabic, polyalkyleneglycols and the like..It is, of course, a prerequisite that all adjuvants used in thepreparation of the pharmaceutical preparations are non-toxic andpharmaceutically acceptable.

For topical administration, the compounds of this invention areexpediently made up in the form of salves, tinctures, creams, solutions,lotions, sprays, suspensions and the like. Ointments, creams andsolutions are preferred. These pharmaceutical preparations for topicaladministration can be prepared by mixing a compound of this invention asthe active ingredient with pharmaceutically acceptable non-toxic, inert,solid or liquid carriers which are customary in such preparations andwhich are suitable for topical administration.

Compositions for topical administration for use according to thisinvention contain on a weight basis the following amount of activecompound: about 0.01% to about 0.3%, preferably about 0.02% to about0.1%, in solutions and about 0.05% to about 5%, preferably about 0.1% toabout 2%, in ointments or creams.

A conventional pharmaceutically acceptable antioxidant, e.g.,tocopherol, N-methyl-γ-tocopheramine, butylated hydroxyanisole orbutylated hydroxytoluene can also be incorporated into thepharmaceutical preparations containing the compounds of this invention.

The compounds represented by formula I can be utilized as salts withpharmaceutically acceptable acids and bases. The salts can be preparedby reacting a carboxylic acid of formula I by conventional means with abase, e.g., alkali metal hydroxides, NaOH or KOH or an amine of formulaI with an organic or inorganic acid, e.g., hydrohalic acid, HCl or HBror benzoic, acetic, citric or lactic acids.

The compounds represented by formula I can be produced by reacting acompound represented by the formula ##STR7## wherein one of R₆ or R₇ is##STR8## and the other of R₆ or R₇ and R₃ and R₄ are hydrogen, loweralkyl thio, lower alkoxy-lower alkyl, hydroxy methyl, halogen, loweralkyl, lower alkoxy, amino, carboxyl, mono(lower alkyl)amino, di(loweralkyl)amino, mono(lower alkyl)amino lower alkyl, di(loweralkyl)aminolower alkyl, hydroxy, lower alkenyl, lower alkenoxy, loweralkanoyl, lower alkanoyloxy, nitro, lower alkoxycarbonyl, loweralkanoylamido or a nitrogen containing heterocycle; m is 0 or 1, A isoxo, --P[X]₃ ⁺ y⁻ or ##STR9## X is aryl, Z is lower alkoxy and y is ananion of an organic acid or an inorganic acid,

with a compound represented by the formula ##STR10## wherein, B is oxowhen A from the compound of formula II is --P[X]₃ ⁺ y⁻ or ##STR11## orwhen said A is oxo, B is --P[X]₃ ⁺ y⁻ or ##STR12## n is 0 or 1 and X, yand Z are the same as in formula II; when B is ##STR13## or --P[X]₃ ⁺y⁻, R₅ is formyl, carboxyl, lower alkoxycarbonyl, loweralkenyloxycarbonyl, lower alkynyloxycarbonyl, di(lower alkyl)carbamoylor N-heterocyclylcarbonyl; when B is oxo, R₅, is carboxyl, loweralkoxymethyl, lower alkanoyloxy methyl, lower alkoxycarbonyl, loweralkenyloxycarbonyl, lower alkynyloxycarbonyl or N-heterocyclylcarbonyl.

In formulas II and III, the sum of m and n is always one.

The "aryl" group denoted by X includes all generally known aryl groups,preferred as mononuclear aryl groups such as phenyl, loweralkyl-substituted phenyl or lower alkoxy-substituted phenyl, e.g.,xylyl, mesityl and p-methoxyphenyl. The inorganic acid anions denoted byy are preferably the chloride, bromide, iodide, and hydrosulfate. Thepreferred organic acid anion denoted by y is tosyloxy.

The products of the reaction between compounds of formula II and formulaIII which contain a carboxyl at R₅, can be esterified or amidated at thecarboxyl. When R_(5') is carboxyl or an ester, the reaction product canbe reduced at R_(5') to form a hydroxymethyl. The hydroxymethyl atR_(5') can be esterified or etherified. The resulting alcohol ester canbe saponified if desired. In cases where R_(5') is a free hydroxymethylor an ester thereof, such groups can be oxidized to form thecorresponding compound where R_(5') is formyl or carboxyl.

The compounds represented by formula II are, in part, novel and arewithin the scope of this invention. Certain novel compounds withinformula II are those represented by the formula ##STR14## wherein one ofR'₆ or R'₇ is ##STR15## and the other of R'₆ or R'₇ and R'₃ and R'₄ arehydrogen, lower alkyl thio, lower alkoxy-lower alkyl, hydroxy methyl,halogen, lower alkyl, lower alkoxy, amino, carboxyl, mono(loweralkyl)amino, di(lower alkyl)amino, mono(lower alkyl)amino lower alkyl,di(lower alkyl)amino lower alkyl, hydroxy, lower alkenyl, loweralkenoxy, lower alkanoyl, lower alkanoyloxy, nitro, loweralkoxycarbonyl, lower alkanoylamido or a nitrogen containingheterocycle; X is aryl and y is an anion of an organic acid or aninorganic acid

and the formula ##STR16## wherein one of R"₆ or R"₇ is ##STR17## and theother of R'₆ or R"₇ and R₃ and R₃ and R₄ are hydrogen, lower alkyl thio,lower alkoxy-lower alkyl, hydroxymethyl, halogen, lower alkyl, loweralkoxy, amino, carboxyl mono(lower alkyl)amino, di(lower alkyl)amino,mono(lower alkyl)amino lower alkyl, di(lower alkyl)amino lower alkyl,hydroxy, lower alkenyl, lower alkenoxy, lower alkanoyl, loweralkanoyloxy, nitro, lower alkoxycarbonyl, lower alkanoylamido or anitrogen containing heterocycle; and Z is lower alkoxy.

In addition some of the compounds wherein one of R'₆ or R'₇ is --CH₂--P[X]⁺ ₃ y⁻ or one of R"₆ or R"₇ is ##STR18## are novel.

The compounds of formula II wherein R₆ or R₇ is --CH₂ --P[X]⁺ ₃ y⁻ or##STR19## can be prepared by treating the corresponding substitutedthiophene with formaldehyde in the presence of a hydrohalic acid, e.g.,concentrated hydrochloric acid, in a solvent such as glacial acetic acidif desired, to form the halide. The halide is then reacted in aconventional manner with a triaryl phosphine in a solvent, preferablytriphenyl phosphine in toluene or benzene, or with a trialkyl phosphite,e.g., triethyl phosphite.

The compounds of formula II wherein R₆ or R₇ is ##STR20## can beprepared by first formylating the corresponding thiophene, for example,in the presence of a Lewis acid. As the formylating agent there can beused an orthoformic acid ester, formyl chloride, dimethylformamide andN-methyl formanilide. Especially suitable Lewis acids are the halides ofzinc, aluminum, titanium, tin and iron, e.g., zinc chloride, aluminumtrichloride, titanium tetrachloride, tin tetrachloride and irontrichloride as well as the halides of inorganic and organic acids suchas phosphorus oxychloride and methane sulfochloride.

If the formylating agent is present in excess, the formylation may becarried out without the addition of a further solvent. In general,however, the formylation should be carried out in an inert solvent,e.g., nitrobenzene or chlorinated hydrocarbons such as methylenechloride. The formulation can be carried out at a temperature between 0°C. and the boiling point of the mixture.

A resulting substituted thiophenecarboxaldehyde can subsequently bechain-lengthened in a conventional manner by condensation with acetonein the cold, i.e., about 0° C.-30° C. in the presence of alkali, e.g.,dilute aqueous sodium hydroxide to give a substitutedthienyl-but-3-en-2-one which can be converted into the correspondingsubstituted thienyl-3-methyl-3-hydroxy-penta-4-en-1-yne by conventionalmeans, e.g., by means of a Grignard reaction by the addition ofacetylene. The resulting acetylenic carbinol can subsequently bypartially hydrogenated in a conventional manner using a partiallydeactivated noble metal catalyst, e.g., Lindlar catalyst. The resultingtertiary ethylenic carbinol can alternatively be synthesized by additionof a vinyl magnesium halide to the substituted thienyl-but-3-en-2-one.

The thus formed tertiary ethylenic carbinol can subsequently beconverted, under allyl rearrangement, into the desired phosphonium salt.

The compounds of formula II wherein R₆ or R₇ is ##STR21## can beprepared by treatment of the tertiary ethylenic carbinol with a triarylphosphine, preferably triphenyl phosphine, in the presence of ahydrohalide such as hydrogen chloride or hydrogen bromide in a solvent,e.g., benzene. The tertiary ethylenic carbinol can, moreover, behalogenated to give result in the compound of formula II where m is 1and A is halide. This halide can be reacted with a trialkyl phosphite,e.g., triethyl phosphite to yield a corresponding phosphonate of formulaII wherein R₆ or R₇ is ##STR22##

Compounds of formula II wherein m is 0 and A is oxo can be prepared, forexample, by formylating a substituted thiophene as described above toform the corresponding thiophene carboxaldehyde.

Compounds of formula II wherein m is 1 and A is oxo can be prepared, forexample, by submitting a substituted thienyl-but-3-en-2-one, describedabove, to a Wittig reaction with ethoxycarbonylmethylene-triphenylphosphorane or with diethyl-phosphonoacetic acidethyl ester. The resulting substitutedthienyl-3-methyl-penta-2,4-dien-1-oic acid ethyl ester is subsequentlyreduced in the cold with a mixed metal hydride, e.g., lithium aluminumhydride, in an organic solvent such as diethyl ether or tetrahydrofuranto yield a substituted thienyl-3-methyl-penta-2,4-dien-1-ol. The dienolis then oxidized with an oxidizing agent such as manganese dioxide in anorganic solvent, e.g., acetone or methylene chloride, at a temperaturebetween 0° C. and the boiling point of the mixture to give thecorresponding substituted thienyl-3-methyl-penta-2,4-dien-1-al.

The compounds represented by formula III are prepared as follows.

Compounds of formula III where n is zero and B is a triarylphosphoniumgroup or a dialkoxyphosphinyl group can be readily prepared by reactingan optionally esterified 3-halomethyl-crotonic acid or an etherified3-halo-methylcrotyl alcohol with a triaryl phosphine in a solvent,preferably with triphenyl phosphine in toluene or benzene, or with atrialkyl phosphite, such as triethyl phosphite.

Compounds of formula III where n is 1 and B is a triarylphosphoniumgroup or a dialkoxyphosphinyl group can be prepared, for example, byreducing the formyl group of the corresponding aldehyde in which n is 1to the hydroxymethyl group using a metal hydride such as sodiumborohydride in an alkanol, e.g., ethanol or isopropanol.

The resulting alcohol can be halogenated using a conventionalhalogenating agent, e.g., phosphorus oxychloride and the resulting8-halo-3,7-dimethyl-octa-2,4,6-triene-1-carboxylic acid ester, a halideof formula III in which n is 1 and B is halogen or a derivative thereofcan be reacted either with a triaryl phosphine in a solvent, preferablytriphenyl phosphine in toluene or benzene, to give a phosphonium salt orwith a trialkyl phosphite, preferably triethyl phosphite, to give thecorresponding phosphonate.

Compounds of formula III where n is zero and B is an oxo group can beprepared, for example, by oxidatively cleaving an optionally esterifiedtartaric acid; for example, using lead tetraacetate at room temperaturein an organic solvent such as benzene. The resulting glyoxalic acidderivative is subsequently condensed in a conventional manner, e.g.,conveniently in the presence of an amine, with propionaldehyde at anelevated temperature, e.g., at a temperature between 60° C. and 110° C.with water cleavage to yield the corresponding 3-formyl-crotonic acidderivative.

Compounds of formula III where n is 1 and B is an oxo group can beprepared, for example, by reacting 4,4-dimethoxy-3-methyl-but-1-en-3-olwith phosgene in the cold, preferably at -10° C. to -20° C., in thepresence of a tertiary amine such as pyridine and condensing theresulting 2-formyl-4-chloro-but-2-ene, a halide of formula III where Bis halogen and n is 0, under conditions of a Wittig reaction with anoptionally esterified 3-formyl-crotonic acid or to an optionallyesterified or etherified 3-formyl-crotyl alcohol to yield thecorresponding aldehyde of formula III.

The reaction of aldehydes of formula II with phosphonium salts orphosphoranes of formula III or aldehydes of formula III with phosphoniumsalts or phosphoranes of formula II to produce compounds of formula Ican be carried out by, for example, either the Wittig or Hornertechniques.

According to the Wittig procedure, the reaction components are reactedwith one another in the presence of an acid binding agent, for example,in the presence of an alkali metal alcoholate such as sodium methylateor in the presence of an optionally alkyl-substituted alkylene oxide,preferably in the presence of ethylene oxide or 1,2-butylene oxide. Ifdesired a solvent, e.g., a chlorinated hydrocarbon such as methylenechloride or dimethylformamide can be used. The reaction is carried outat a temperature between room temperature and the boiling point of thereaction mixture.

According to the Horner procedure, the reaction components are reactedwith one another with the aid of a base and preferably in the presenceof an inert organic solvent; for example, with the aid of sodium hydridein benzene, toluene, dimethylformamide, tetrahydrofuran, dioxan or1,2-dimethoxyethane or with the aid of an alkali metal alcoholate in analkanol, e.g., sodium methylate in methanol at a temperature between 0°C. and the boiling point of the reaction mixture.

For convenience, the reactions described hereinbefore can, in somecases, be carried out without isolating the phosphonium salt orphosphonate from the medium in which it is prepared.

A carboxylic acid of formula I can be converted by conventional means,e.g., by treatment with thionyl chloride, preferably in pyridine, intoan acid chloride which can be converted by treatment with ammonia orwith an amine into an amide and by reaction with an alkanol into anester.

A carboxylic acid ester of formula I can be hydrolyzed by conventionalmeans, e.g., by treatment with an alkali, preferably aqueous-alcoholicsodium hydroxide or potassium hydroxide, at a temperature between roomtemperature and the boiling point of the mixture and then amidatedeither via an acid halide or as described hereinafter.

A carboxylic acid ester of formula I can be converted directly into thecorresponding amide, for example, by treatment with lithium amide. Thelithium amide is advantageously treated with the ester at roomtemperature.

A carboxylic acid or a carboxylic acid ester of formula I can be reducedby conventional means to give the corresponding alcohol of formula I.The reduction is advantageously carried out using a metal hydride oralkyl metal hydride in an inert solvent. The preferred hydrides are themixed metal hydrides such as lithium aluminum hydride orbis[methoxyethylenoxy]-sodium aluminum hydride. Suitable solvents are,inter alia, ether, tetrahydrofuran or dioxan when lithium aluminumhydride is used and ether, hexane, benzene or toluene when diisobutylaluminum hydride or bis[methoxy-ethylenoxy]-sodium aluminum hydride isused.

An alcohol of formula I can be etherified with an alkyl halide, e.g.,ethyl iodide, in the presence of a base, preferably sodium hydride, inan organic solvent such as dioxan, tetrahydrofuran, 1,2-dimethoxyethane,dimethylformamide at a temperature between 0° C. and room temperature.

An alcohol of formula I can also be esterified by treatment with analkanoyl halide or anhydride, expediently in the presence of a base,e.g., pyridine or triethylamine at a temperature between roomtemperature and the boiling point of the mixture.

An alcohol ester can be saponified by conventional means, for example,by the process previously described in connection with the hydrolysis ofa carboxylic acid ester.

An alcohol of formula I or an ester thereof can be oxidized byconventional means to give the corresponding acid of formula I. Theoxidation is advantageously carried out with silver (I) oxide and alkaliin water or in an organic water-miscible solvent at a temperaturebetween room temperature and the boiling point of the mixture.

An amine of formula I forms addition salts with inorganic and organicacids. Examples of such salts are those formed with hydrohalic acids,preferably hydrochloric or hydrobromic acid, with other mineral acids,e.g., sulphuric acid and with organic carboxylic acids, e.g., benzoicacid, acetic acid, citric acid or lactic acid.

A carboxylic acid of formula I forms salts with bases, preferably withalkali metal hydroxides, e.g., sodium hydroxide or potassium hydroxide.

The compounds of formula I can occur as cis/trans mixtures which, ifdesired, can be separated into the cis and trans components orisomerised to the all-trans compounds by conventional means.

The following examples illustrate the invention. In the examples, theether utilized was diethyl ether. In the examples concentratedhydrochloric acid denotes an aqueous solution containing about 37% byweight hydrochloric acid. The term 35% formaldehyde which appears in theexamples indicate an aqueous solution containing 35% formaldehyde.

The sodium hydride (50-60%) utilized in the examples refers to a mineraloil suspension containing 30 to 60% by weight sodium hydride.

EXAMPLE 1 2,4,5-Trimethyl-3-chloromethyl-thiophene

24.6 G. of 2,3,5-trimethyl-thiophene, 14.8 g. of freshly distilledchloromethyl methyl ether and 52 g. of glacial acetic acid were combinedin a glass pressure bottle and stirred at room temperature for 41/2hours. The resulting reaction mixture was poured into ice water, stirredfor 10 min. and extracted with benzene. The combined benzene extractswere washed twice with saturated sodium chloride solution, dried oversodium sulfate, filtered and evaporated. The resulting2,4,5-trimethyl-3-chloromethyl-thiophene was used for the next stepwithout any further purification.

EXAMPLE 2 (2,4,5-Trimethyl-3-thenyl)triphenyl phosphonium chloride

33.2 G. of 2,4,5-trimethyl-3-chloromethyl-thiophene and 55.0 g. oftriphenyl phosphine were dissolved in 200 ml. of benzene. The resultingmixture was refluxed overnight under argon and then cooled to roomtemperature. The precipitated white phosphonium salt which formed wascollected by filtration, washed several times with cold benzene anddried at 80° C. under high vacuum to yield(2,4,5-trimethyl-3-thenyl)triphenyl phosphonium chloride, m.p. 236°-237°C.

EXAMPLE 3 Alltrans-3,7-dimethyl-9-(2,4,5-trimethyl-3-thienyl)-2,4,6,8-nonatetraenicacid ethyl ester

10 G. of (2,4,5-trimethyl-3-thenyl)triphenyl phosphonium chloride wassuspended in 200 ml. of butylene oxide then 5.2 g. of3-methyl-7-formyl-octa-2,4,6-trienoic acid ethyl ester were added. Theresulting mixture was refluxed under argon with stirring until a clearsolution resulted. After heating for another 15 min. the solvent wasevaporated. The oily residue was diluted with about 300 ml. of amethanol/water mixture (ratio 6:4) and extracted four times with hexane.The combined hexane solutions were washed once with methanol/water (6:4)and twice with pure water, dried with sodium sulfate, filtered andevaporated. The resulting crude product was purified by columnchromatography (hexane/5% ether) and recrystallized from hexane/ether(4:1) to give alltrans-3,7-dimethyl-9-(2,4,5-trimethyl-3-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester, m.p. 88°-89° C.

EXAMPLE 4 Alltrans-3,7-dimethyl-9-(2,4,5-trimethyl-3-thienyl)-2,4,6,8-nonatetraenoicacid

4.35 G. of alltrans-3,7-dimethyl-9-(2,4,5-trimethyl-3-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester was dissolved in 30 ml. of ethanol and a solution of 3g. of potassium hydroxide in 6 ml. of water and 6 ml. of ethanol wasadded. The resulting reaction mixture was stirred under argon for 2.5hours at 50° C. After cooling, the resulting solution was poured on icewater, acidified with 3 N sulfuric acid and extracted several times withmethylene chloride. The organic phase was washed twice with water, driedover sodium sulfate, filtered and evaporated. The resulting crudematerial was recrystallized from ethyl acetate to yield alltrans-3,7-dimethyl-9-(2,4,5-trimethyl-3-thienyl)-2,4,6,8-nonatetraenoicacid, m.p. 208°-212° C.

EXAMPLE 5 Alltrans-N-ethyl-3,7-dimethyl-9-(2,4,5-trimethyl-3-thienyl)-2,4,6,8-nonatetraenamide

1.78 G. of alltrans-3,7-dimethyl-9-(2,4,5-trimethyl-3-thienyl)-2,4,6,8-nonatetraenoicacid were suspended in 20 ml. of benzene. 563 Mg. of phosphorustrichloride were dropped into the suspension at room temperature. Afterstirring at 30° C. for about 3 hours, the acid was dissolved and a redsolution of the acid chloride resulted. The red solution was droppedinto a mixture of 800 mg. of ethylamine and 20 ml. of methylene chlorideat 5°-10° C. After stirring for one hour at room temperature, theresulting reaction mixture was diluted with methylene chloride, pouredinto a saturated sodium chloride solution and extracted three times withmethylene chloride. The combined organic phases were washed once withsaturated sodium chloride solution, dried over sodium sulfate, filteredand evaporated. Recrystallization from ethyl acetate gave alltrans-N-ethyl-3,7-dimethyl-9-(2,4,5-trimethyl-3-thienyl)-2,4,6,8-nonatetraenamide,m.p. 184°-187° C.

EXAMPLE 6 2-Hydroxymethyl-3,4,5-trimethyl-thiophene

1.9 G. of 3,4,5-trimethyl-2-thiophenecarboxaldehyde were dissolved in 20ml. of ethanol. The resulting solution was cooled to 0°-5° C. and 125mg. of sodium borohydride were added in small portions. The resultingreaction mixture was stirred at room temperature for 3 hours, pouredinto ice water, extracted with ethyl acetic, dried with sodium sulfate,filtered and evaporated. The resulting crystalline2-hydroxymethyl-3,4,5-trimethyl-thiophene had m.p. 45°-48° C.

EXAMPLE 7 (3,4,5-Trimethyl-2-thenyl)triphenyl phosphonium bromide

2.2 G. of 2-hydroxymethyl-3,4,5-trimethyl-thiophene were dissolved in 25ml. of acetonitrile and 4.6 g. of triphenylphosphonium bromide wereadded. The resulting reaction mixture was heated to 50° C. for 3 hours.After evaporation of the solvent, the residue which formed was dilutedwith ethyl acetate, heated briefly and filtered. The crystalline(3,4,5-trimethyl-2-thenyl)-triphenyl phosphonium bromide obtained wasdried at 50° C. under high vacuum and had m.p. 208°-215° C.

EXAMPLE 8 Alltrans-3,7-dimethyl-9-(3,4,5-trimethyl-2-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester

3.2 G. of (3,4,5-trimethyl-2-thenyl)triphenyl phosphonium bromide weresuspended in 80 ml. of butylene oxide and 1.5 g. of3-methyl-7-formyl-octa-2,4,6-trienoic acid ethyl ester were added. Theresulting mixture was refluxed under argon for one hour which thesolvent was evaporated. The residue which formed was diluted with amixture of methanol/water (6:4) and extracted four times with hexane.The combined hexane solutions were washed once with methanol/water (6:4)and twice with pure water, dried with sodium sulfate, filtered andevaporated. The resulting crude product was purified by columnchromatography on silica gel and elution with hexane/5% ether.Recrystallization of the alltrans-3,7-dimethyl-9-(3,4,5-trimethyl-2-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester so obtained from hexane/1% ethyl acetate gave yellowcrystals, m.p. 96°-98° C.

EXAMPLE 9 (3-methyl-2-thenyl)triphenyl phosphonium bromide

2-Hydroxymethyl-3-methyl-thiophene (4.5 g.) was dissolved in 90 ml. ofacetonitrile and 12.3 g. of triphenylphosphonium bromide were added. Thereaction mixture was heated to 70° C. for 3 hours. After cooling theresulting precipitate was filtered off, washed with benzene and dried at80° C. under high vacuum. The resulting(3-methyl-2-thenyl)triphenylphosphonium bromide has a m.p. 266°-269° C.

EXAMPLE 10 Alltrans-3,7-dimethyl-9-(3-methyl-2-thienyl)-2,4,6,8-nonatetraenoic acidethyl ester

Sodium hydride (1.16 g. of a 50% suspension in mineral oil) was washedthree times with pentane, dried and suspended in 50 ml. ofdimethylformamide. At 0° C. a suspension of 7.5 g. of(3-methyl)-2-thenyl)triphenylphosphonium bromide in 25 ml. ofdimethylformamide was dropped in. After stirring for 15 minutes, asolution of 3.74 g. of 3-methyl-7-formyl-octa-2,4,6-trienoic acid ethylester in 40 ml. of dimethylformamide was dropped in. After stirring for2.5 hours at room temperature the reaction mixture was poured into amethanol/water mixture (ratio 6:4) and extracted several times withhexane. The combined organic phases were washed once with methanol/water(6:4), dried over sodium sulfate, filtered and evaporated. The crudeproduct was purified by recrystallization from hexane to giveall-trans-3,7-dimethyl-9-(3-methyl-2-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester, m.p. 86°-87° C.

EXAMPLE 11 (5-methyl-2-thenyl)triphenylphosphonium bromide

2-Hydroxymethyl-5-methyl-thiophene (4.6 g.) was dissolved in 100 ml. ofacetonitrile and 12.2 g. of triphenylphosphonium bromide were added. Thereaction mixture was heated to 75° C. for 2.5 hours. After cooling theresulting precipitate was filtered off, washed with benzene and dried at80° C. under high vacuum. The resulting(5-methyl-2-thenyl)triphenylphosphonium bromide has a m.p. 262°-266° C.

EXAMPLE 12All-trans-3,7-dimethyl-9-(5-methyl-2-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester

Sodium hydride (1.45 g. of a 50% suspension in mineral oil) was washedthree times with pentane, dried and suspended in 75 ml. ofdimethylformamide. At 0° C. a suspension of 10.3. g of(5-methyl-2-thenyl)triphenylphosphonium bromide in 50 ml. ofdimethylformamide was dropped in. After stirring for 15 minutes, asolution of 6.25 g. of 3-methyl-7-formyl-octa-2,4,6-trienoic acid ethylester in 50 ml. of dimethylformamide was dropped in. After stirring for1 hour at room temperature the reaction mixture was poured into amethanol/water mixture (ratio 6:4) and extracted several times withhexane. The combined organic phases were washed once with methanol/water(6:4), dried over sodium sulfate, filtered and evaporated. The crudeproduct was purified by recrystallization from hexane to giveall-trans-3,7-dimethyl-9-(5-methyl-2-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester, m.p. 92°-93° C.

EXAMPLE 13 (2,5-dimethyl-3-thenyl)triphenylphosphonium chloride

Triphenylphosphine (11.8 g.) and 7.0 g. of2,5-dimethyl-3-chloromethylthiophene were dissolved in 100 ml. oftoluene. The mixture was refluxed overnight under argon, cooled to roomtemperature and the precipitated white phosphonium salt was collected byfiltration, washed several times with cold benzene and dried at 80° C.under high vacuum. The resulting(2,5-dimethyl-3-thenyl)-triphenylphosphonium chloride has a m.p.246°-250° C.

EXAMPLE 14All-trans-3,7-dimethyl-9-(2,5-dimethyl-3-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester

(2,5-Dimethyl-3-thenyl)triphenylphosphonium chloride (7.0 g.) weresuspended in 200 ml. of butylene oxide and 3.4 g. of3-methyl-7-formyl-octa-2,4,6-trienoic acid ethyl ester were added. Themixture was refluxed under argon for 5.5 hrs. The resulting solution waspoured into 500 ml. of a methanol/water mixture (ratio 6:4), extractedfour times with hexane, washed with methanol/water, dried over sodiumsulfate, filtered and evaporated. The crude product was purified byrecrystallization from hexane to give alltrans-3,7-dimethyl-9-(2,5-dimethyl-3-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester, m.p. 119°-121° C.

EXAMPLE 15 (3,4,5-tribromo-2-thenyl)triphenylphosphonium chloride

Triphenylphosphine (9.0 g.) and 10.4 g. of3,4,5-tribromo-2-chloromethylthiophene were dissolved in 200 ml. oftoluene. The mixture was refluxed overnight under argon, cooled to roomtemperature and the precipitated phosphonium salt was collected byfiltration, washed several times with cold benzene and dried at 80° C.under high vacuum. The resulting(3,4,5-tribromo-2-thenyl)triphenylphosphonium chloride has a m.p.248°-249° C.

EXAMPLE 16 Alltrans-3,7-dimethyl-9-(3,4,5-tribromo-2-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester

Following the procedure of Example 10 (3,4,5-tribromo-2-thenyl)triphenylphosphonium chloride is condensed with7-formyl-3-methyl-octa-2,4,6-trienoic acid ethyl ester to form alltrans-3,7-dimethyl-9-(3,4,5-tribromo-2-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester, which is recrystallized from hexane/5% ethyl acetate,m.p. 84°-86° C.

EXAMPLE 17 2-chloromethyl-3,4-dibromo-5-methyl-thiophene

A solution of 11.7 g. of 2-methyl-3,4-dibromo-thiophene in 30 ml. ofacetic acid was added to 60 ml. of concentrated hydrochloric acid. Afterdropping in 4.1 g of a 37% aqueous solution of formaldehyde the mixturewas heated to 70° C. for one hour. The reaction mixture was cooled,diluted with water and extracted with ether. The combined organic phaseswere washed with water, sodium bicarbonate and water, dried over sodiumsulfate, filtered and evaporated to give2-chloromethyl-3,4-dibromo-5-methyl-thiophene.

EXAMPLE 18 (3,4-dibromo-5-methyl-2-thenyl)triphenyl phosphonium chloride

(3,4-Dibromo-5-methyl-2-thenyl)triphenyl phosphonium chloride can beprepared in a manner analogous to that described in Example 13 byreaction of 2-chloromethyl-3,4-dibromo-5-methyl-thiophene with triphenylphosphine, m.p. 215°-216° C.

EXAMPLE 19 Alltrans-3,7-dimethyl-9-(3,4-dibromo-5-methyl-2-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester

By the procedure of Example 14 (3,4-dibromo-5-methyl-2-thenyl)triphenylphosphonium chloride is condensed with7-formyl-3-methyl-octa-2,4,6-trienoic acid ethyl ester to form alltrans-3,7-dimethyl-9-(3,4-dibromo-5-methyl-2-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester, which is recrystallized from hexane/ethyl acetate(1:1), m.p. 150°-153° C.

EXAMPLE 20 Glyoxalic acid butyl ester

1775 g. of lead tetraacetate (90%) are gradually introduced within 30minutes at 25°-30° C. into a solution of 1000 g. of L(+)-tartaric aciddibutyl ester in 3850 ml. of benzene. The reaction mixture issubsequently stirred for 1 hour at room temperature. The sediment isfiltered off and extracted with 500 ml. of benzene. The benzene extractis evaporated under reduced pressure. The remaining glyoxalic acid butylester boils, after rectification, at 50°-65° C./12 mm Hg.

EXAMPLE 21 3-formyl-crotonic acid butyl ester

836 G. of the obtained glyoxalic acid butyl ester are introduced into376 g. of propionaldehyde. The mixture is treated dropwise at 60° C.with 40.8 g. of di-n-butylamine. In so doing, the reaction temperatureshould not rise higher than 105° C. The reaction mixture is then stirredfor 2 hours at 116°-111° C., cooled and taken up in ether. The diethylether extract is washed successively with 500 ml. of 1 N sulphuric acid,700 ml. of water, 1000 ml. of 5% by weight aqueous sodium bicarbonatesolution and subsequently with 1000 ml. of water, dried over sodiumsulphate and evaporated under reduced pressure. The remaining3-formylcrotonic acid butyl ester boils, after rectification, at93°-105° C./14 mm. Hg.; n_(D) ²⁵ =1.

EXAMPLE 22 4,4-dimethoxy-3-methyl-but-1-yn-3-ol

After the addition of a slight amount of iron (III) nitrate, 2700 ml. ofliquid ammonia are treated portion-wise with stirring and cooling with169.5 g. of potassium. As soon as the initially blue coloration hasdisappeared, i.e., after about 30-45 minutes, acetylene gas in a streamof 3 l/min. is led in until the dark coloration of the reaction mixturebecomes lighter. Then, the gas stream is reduced to 2 l/min. and themixture treated dropwise with a solution of 500 g. ofmethylglyoxal-dimethylacetal in 425 ml. of abs. diethyl ether. Theintroduction of acetylene is continued for 1 hour with stirring. Thereaction mixture is subsequently treated portion-wise with 425 g. ofammonium chloride, gradually warmed to 30° C. within 12 hours withevaporation of the ammonia and extracted with 1600 ml. of diethyl ether.The ether extract is dried over sodium sulfate and evaporated underreduced pressure. The remaining 4,4-dimethoxy-3-methylbut-1-yn-3-olboils, after rectification, at 33° C./0.03 mm Hg; n_(D) ²⁵ =1.4480.

EXAMPLE 23 4,4-dimethoxy-3-methyl-but-1-en-3-ol

198 G. of 4,4-dimethoxy-3-methyl-but-1-yn-3-ol are dissolved in 960 ml.of high-boiling petroleum ether and, after the addition of 19.35%palladium catalyst and 19.3 g. of quinoline, hydrogenated under normalconditions. After the uptake of 33.5 l. of hydrogen, the hydrogenationis stopped. The catalyst is filtered off. The filtrate is evaporatedunder reduced pressure. The remaining4,4-dimethoxy-3-methyl-but-1-en-3-ol boils, after rectification, at70°-72° C./18 mm Hg.

EXAMPLE 24 2-formyl-4-chloro-but-2-ene

195 Ml. of phosgene are led into 1570 ml. of carbon tetrachloride at-10° C. After the addition of 213 g. of pyridine, the solution istreated dropwise at a temperature of -10° to -20° C. with 3274,4-dimethoxy-3-methyl-but-1-en-3-ol. The reaction mixture is slowlywarmed to 25° C. with stirring, stirred for a further 3 hours at roomtemperature, cooled to 15° C. and treated with 895 ml. of water. Theaqueous phase is separated and rejected. The organic phase is treated,after standing for 12 hours in the cold, with 448 ml. of 5% by weightaqueous sulphuric acid, stirred for 5 hours, then washed with water,dried over sodium sulphate and evaporated under reduced pressure. Theremaining 2-formyl-4-chloro-but-2-ene boils, are rectification, at37°-40° C./1.8 mm Hg; n_(D) ²⁵ =1.4895.

EXAMPLE 25 2-formyl-but-2-ene-4-triphenyl-phosphonium chloride

165.7 G. of 2-formyl-4-chloro-but-2-ene are dissolved in 840 ml. ofbenzene and treated with 367 g. of triphenyl phosphine. The reactionmixture is heated to boiling under reflux conditions for 12 hours in anitrogen atmosphere, then cooled to 20° C. The precipitated2-formyl-but-2-ene-4-triphenyl-phosphonium chloride melts, after washingwith benzene and drying, at 250°-252° C.

EXAMPLE 26 7-formyl-3-methyl-octa-2,4,6-trien-1-oic acid butyl ester

212.6 G. of 2-formyl-but-2-ene-4-triphenyl-phosphonium chloride and 95g. of 3-formyl-crotonic acid butyl ester are introduced into 1100 ml. ofbutanol and treated at 5° C. with a solution of 57 g. of triethylaminein 60 ml. of butanol. The reaction mixture is subsequently stirred for 6hours at 25° C., then cooled and introduced into water and thoroughlyextracted with hexane. The hexane phase is washed first repeatedly withmethanol/water (6:4 parts by volume), then with water, dried over sodiumsulphate and filtered. The filtrate is isomerized for 12 hours byshaking with iodine. The iodine is removed by the addition of sodiumthiosulphate. The filtrate is washed again with water, dried andevaporated under reduced pressure. The remaining7-formyl-3-methyl-octa-2,4,6-trien-1-oic acid butyl ester boils, afterrectification, at 102°-105° C./0.09 mm Hg.

EXAMPLE 27 8-diethoxy-phosphono-3,7-dimethyl-octa-2,4,6-trien-1-oic acidethyl ester

3.03 G. of 8-bromo-3,7-dimethyl-octa-2,4,6-trien-1-oic acid ethyl esterare heated with 1.66 g. of triethylphosphite slowly to 125° C. Thesurpus bromo ester is distilled off. The residue is cooled and pouredinto ice and extracted with diethyl ether and an aqueous solution ofsodium-hydrogen carbonate, dried and evaporated under reduced pressure.The remaining 8-diethoxy-phosphono-3,7-dimethyl-octa-2,4,6-trien-1-oicacid ethyl ester is immediately treated, as described in Example 28,with 2,4,5-trimethyl-3-thiophenecarboxaldehyde.

EXAMPLE 283,7-dimethyl-9-(2,4,5-trimethyl-3-thienyl)-2,4,6,8-nonatetraenoic acidethyl ester

1.7 G. of 8-diethoxy-phosphono-3,7-dimethyl-octa-2,4,6-trienoic acidethyl ester are introduced in 8.0 ml. of tetrahydrofuran. The solutionis cooled to 0° C. after addition of 0.27 g. of sodium hydride (50-60%),then stirred 30 minutes at 0° C. and thereafter a solution of 1.0 g. of2,4,5-trimethyl-3-thiophenecarboxaldehyde in 5 ml. of tetrahydrofuran isadded dropwise during 15 minutes. The reaction mixture is stirred 7hours at room temperature, then poured into ice and, after addition of 2N hydrochloric acid, extracted with diethyl ether. The ether extract iswashed neutral with water, dried over sodium sulfate and evaporatedunder reduced pressure. The remaining3,7-dimethyl-9-(2,4,5-trimethyl-3-thienyl)-2,4,6,8-nonatetraenoic acidethyl ester is recrystallized from hexane, m.p. 88°-89° C. Instead ofsodium hydride (0.27 g.), employed above, an alkali metal alcoholate canalso be used as condensation agent, e.g., sodium ethylate (0.125 g. ofsodium in 5 ml. ethanol).

EXAMPLE 293,7-dimethyl-9-(2,4,5-trimethyl-3-thienyl)-2,4,6,8-nonatetraenoic acidethyl ester

1.9 G. of 2,4,5-trimethyl-3-thiophenecarboxaldehyde and 6.75 g. of(7-ethoxycarbonyl-2,6-dimethyl-2,4,6-heptatrienyl)triphenyl phosphoniumbromide are dissolved in 50 ml. of dry dimethylformamide. The solutionis treated at 10° C. dropwise with a solution of 0.29 g. of sodium in 8ml. of ethanol. The mixture is subsequently stirred for 4 hours at roomtemperature, then introduced into 100 ml. of methanol/water 60:40 partsby volume and thoroughly extracted with hexane. The hexane extract iswashed with methanol/water (60:40 parts by volume, then with water,dried over sodium sulfate and evaporated. There is obtained3,7-dimethyl-9-(2,4,5-trimethyl-3-trienyl)-2,4,6,8-nonatetraenoic acidethyl ester, which melts after recrystallization from hexane at 88°-89°C.

EXAMPLE 30 8-hydroxy-3,7-dimethyl-octa-2,4,6,-trien-1-oic acid ethylester

36 G. of 7-formyl-3-methyl-octa-2,4,6-trien-1-oic acid ethyl ester aredissolved in 600 ml. of absolute ethanol. The solution is treatedportionwise with 1.8 g. of sodium borohydride. The mixture is stirredfor 2 hours at 10° C. then poured onto ice water and 3 N aqueoushydrochloric acid and extracted with ether. The ether extract is washedsuccessively with water, a saturated aqueous sodium bicarbonate solutionand once more with water, dried over sodium sulfate and evaporated.There is obtained 8-hydroxy-3,7-dimethyl-octa-2,4,6-trien-1-oic acidethyl ester.

EXAMPLE 31 8-bromo-3,7-dimethyl-octa-2,4,6-trien-1-oic acid ethyl ester

36.5 G. of 8-hydroxy-3,7-dimethyl-octa-2,4,6-trien-1-oic acid ethylester are dissolved in 380 ml. of ether. The solution is cooled to 0°C., and after the addition of 3 drops of pyridine treated dropwise with28.6 g. of phosphorous tribromide in 120 ml. of hexane. The mixture isstirred for 20 minutes at 0° C., then poured onto ice water andextracted with ether. The ether extract is washed successively withwater, a saturated aqueous sodium bicarbonate solution and again withwater, dried over sodium sulfate and evaporated. There is obtained8-bromo-3,7-dimethyl-octa-2,4,6-trien-1-oic acid ethyl ester.

EXAMPLE 321-ethoxycarbonyl-2,6-dimethyl-hepta-1,3,5-trien-7-triphenylphosphoniumbromide

43.7 G. of 8-bromo-3,7-dimethyl-octa-2,4,6-trien-1-oic acid ethyl esterare dissolved in 500 ml. of benzene and treated with 42.0 g. oftriphenylphosphine. The mixture is stirred for 12 hours at roomtemperature, then cooled at 0° C. The precipitated1-ethoxycarbonyl-2,6-dimethyl-hepta-1,3,5-trien-7-triphenylphosphoniumbromide melts at 193°-194° C.

EXAMPLE 33 2,4-dimethyl-5-chloro-thiphene

2.5 G. of 2,4-dimethyl-thiophene are dissolved in 45 ml. of methylenedichloride and 3.3 g. of sulfuryl chloride are dropped in. The mixtureis kept at room temperature for 0.5 hour and then refluxed for 2 hours.The reaction mixture is poured into water, extracted with hexane, washedwith saturated sodium chloride solution, dried over sodium sulfate,filtered and evaporated. Distillation gave2,4-dimethyl-5-chloro-thiophene, b.p. 73°-75° C./18 mm.

EXAMPLE 34 2,4-dimethyl-3-chloromethyl-5-chloro-thiophene

3.04 G. of 2,4-dimethyl-5-chloro-thiophene are dissolved in 60 ml. ofacetic acid and 2.1 g. of formalin and 32 ml. of concentratedhydrochloric acid are added. The mixture is stirred at room temperaturefor 2 hours, then poured into ice water and extracted with hexane. Theorganic solution is washed with 5% sodium bicarbonate solution, dried,filtered and evaporated to yield2,4-dimethyl-3-chloromethyl-5-chloro-thiophene.

EXAMPLE 35 (2,4-dimethyl-5-chloro-3-thenyl)triphenyl phosphoniumchloride

(2,4-dimethyl-5-chloro-3-thenyl)triphenyl phosphonium chloride can beprepared in a manner analogous to that described in Example 13 byreaction of 2,4-dimethyl-3-chloromethyl-5-chloro-thiophene withtriphenyl phosphine, m.p. 246°-251° C.

EXAMPLE 36 Alltrans-3,7-dimethyl-9-(2,4-dimethyl-5-chloro-3-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester

By the procedure of Example 14 (2,4-dimethyl-5-chloro-3-thenyl)triphenylphosphonium chloride is condensed with7-formyl-3-methyl-octa-2,4,6-trienoic acid ethyl ester to form alltrans-3,7-dimethyl-9-(2,4-dimethyl-5-chloro-3-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester, which is recrystallized from hexane, m.p. 109°-110° C.

EXAMPLE 37Ethyl-3,7-dimethyl-9-(2,5-dichloro-3-thienyl)-nona-2,4,6,8-tetraenoate

To a cold (-10° C.) suspension of 1.02 g. (2 mmoles) of crude(2,5-dichloro-3-thenyl)-triphenyl phosphonium bromide in 20 ml. of dryether, 0.82 ml. (2 mmoles) of a 2.45 M solution of n-butyl lithium inhexane was added slowly via a syringe. After the addition was complete,the mixture was allowed to stir at -10° C. for 10 minutes. Then asolution of 416 mg. (2 mmoles) of ethyl3,7-dimethyl-7-formyl-2,4,6-octatrienoate was added at 0°-2° C. Themixture was allowed to warm up to room temperature for 11/2 hours andpoured into 25 ml. of sodium chloride solution. Some brown solid wasfiltered off and the organic layer of the filtrate was separated andwashed with two 50 ml. portions of sodium chloride solution, and driedover sodium sulfate. Evaporation of the solvent gave a yellow solidwhich was extracted with several 25 ml. of hexane. The hexane extractswere combined and concentrated to yield a yellow solid which waspurified by chromatography on 45 g. of silica gel packed in hexanecontaining 2% ether. Elution with this solvent mixture gave ethyl3,7-dimethyl-9-(2,5-dichloro-3-thienyl)-nona-2,4,6,8-tetraenoate.

EXAMPLE 38 (2,5-dichloro-3-thenyl)triphenyl phosphonium bromide

2,5-Dichloro-3-bromomethyl thiophene (22 g., 90 mmoles) was mixed with26 g. (99 mmoles) of triphenyl phosphine and 150 ml. of benzene. Themixture was heated to the reflux for 21/2 hours, cooled and filtered togive (2,5-dichloro-3-thenyl)triphenyl phosphonium bromide, m.p.208°-215° C.

EXAMPLE 39 Wet Granulation Formulation--250 mg. tablets

    ______________________________________                                                                 Per Tablet                                           ______________________________________                                        all trans-N-ethyl-3,7-dimethyl-9-(2,4,5-trimethyl-3-                          thienyl)-2,4,6,8-nonatetraenamide-2% excess                                                              255 mg.                                            Modified Starch            25 mg.                                             Pregelatinized starch      25 mg.                                             Microcrystalline cellulose 35 mg.                                             Lactose anhydrous          30 mg.                                             Magnesium stearate         3 mg.                                              Talc                       7 mg.                                              Total Weight               380 mg.                                            ______________________________________                                    

Procedure:

1. Mix all ingredients, except items No. 6 and 7, in a suitable mixer.Mill and mix.

2. Granulate with water to a uniform wet consistency. Mill and spread iton trays.

3. Dry overnight in a suitable dryer.

4. Mill and prepare a premix with magnesium stearate and talc. Mix for 5minutes.

5. Compress on a suitable press.

EXAMPLE 40 Direct Compression Formulation--25 mg. tablets

    ______________________________________                                                                 Per Tablet                                           ______________________________________                                        all trans-N-ethyl-3,7-dimethyl-9-(2,4,5-trimethyl-3-                          thienyl)-2,4,6,8-nonatetraenamide-2% excess                                                              25.5 mg.                                           Lactose anhydrous          172.5 mg.                                          Microcrystalline cellulose (pH 101)                                                                      25 mg.                                             Starch                     25 mg.                                             Magnesium stearate          2 mg.                                             Total Weight               250 mg.                                            ______________________________________                                    

Procedure:

1. Mix all ingredients, except item No. 5, in a suitable mixer.

2. Make a premix with magnesium stearate and add to the mix in Step 1.Mix for 5 minutes.

3. Compress on a suitable press.

EXAMPLE 41 Direct Compression Formulation--25 mg. tablets

    ______________________________________                                                                 Per Tablet                                           ______________________________________                                        all trans-3,7-dimethyl-9-(2,4,5-trimethyl-3-thienyl)-                         2,4,6-8-nonatetraenoic acid ethyl ester-2% excess                                                        25.5 mg.                                           Lactose anhydrous          172.5 mg.                                          Microcrystalline cellulose (pH 101)                                                                      25 mg.                                             Starch                     25 mg.                                             Magnesium stearate         2 mg.                                              Total Weight               250 mg.                                            ______________________________________                                    

Procedure:

1. Mix all ingredients, except item No. 5, in a suitable mixer.

2. Make a premix with magnesium stearate and add to the mix in Step 1.Mix for 5 minutes.

3. Compress on a suitable press.

EXAMPLE 42 Wet Granulation Formulations--250 mg. tablets

    ______________________________________                                                                 Per Tablet                                           ______________________________________                                        all trans-3,7-dimethyl-9-(2,4,5-trimethyl-3-thienyl)-                         2,4,6,8-nonatetraenoic acid ethyl ester-2% excess                                                        255 mg.                                            Modified Starch            25 mg.                                             Pregelatinized starch      25 mg.                                             Microcrystalline cellulose 35 mg.                                             Lactose anhydrous          30 mg.                                             Magnesium stearate         3 mg.                                              Talc                       7 mg.                                              Total Weight               380 mg.                                            ______________________________________                                    

Procedure:

1. Mix all ingredients, exept items No. 6 and 7, in a suitable mixer.Mill and mix.

2. Granulate with water to a uniform wet consistency. Mill and spread iton trays.

3. Dry overnight in a suitable dryer.

4. Mill and prepare a premix with magnesium stearate and talc. Mix for 5minutes

5. Compress on a suitable press.

EXAMPLE 43 3-chloromethyl-2,5-dimethylthiophene

36.4 G., 0.325 mol. of 2,5-dimethylthiophene, 24.7 g. (0.307 mol) offreshly distilled chloromethyl methyl ether (b.p. 58°-60° C.) and 87.0g. of glacial acetic acid were combined in a glass pressure bomb andstirred at room temperature for 5 hours. After 0.5 to 1 hr. anexothermic reaction took place. The reaction mixture was cooledexternally in an ice bath so that the reaction temperature did notexceed 35° C. The color of the mixture changed from green to blue. Theresulting solution was poured into ice water, stirred for ten minutesand extracted four times with benzene. The combined benzene extractswere washed twice with saturated sodium chloride solution, dried andevaporated. The resulting liquid was quickly distilled and the materialwhich boiled at 90°-125° C./18 mm. was collected. A second distillationyielded the pure product, b.p. 109°-115° C./18 mm.

EXAMPLE 44 2,3,5-trimethylthiophene

9 G. of Pd-C (5%) were added to a solution of 44.0 g. (0.274 mol) of2,5-dimethyl-3-chloromethyl-thiophene in 500 ml. of ether and 41.5 g.(0.41 mol) of triethylamine (57 ml.). The resulting reaction mixture washydrogenated under low pressure (200 psi) at room temperature.Additional catalyst is added until no more hydrogen was taken up. Thereaction took approximately 6 hrs. and about 6.1 l. of hydrogen wastaken up. The catalyst was filtered off and the solvent was evaporatedat normal pressure on a small Vigreux column. Distillation of theresulting liquid gave the final product, 2,3,5-trimethylthiophene, b.p.85°-89° C./61 mm.

EXAMPLE 45 3-ethoxycarbonyl-4-methyl-hexane-2,5-dione

7.3 G., 0.317 mol of sodium was dissolved in 125 ml. of absoluteethanol. 87.0 G. (0.669 mol) of ethyl acetoacetate were added to theresulting solution of sodium ethoxide in the cold. The reaction mixturewas heated to reflux and 48.6 g. (0.322 mol) of freshly distilled3-bromo-2-butanone were added dropwise with stirring over a period of 30min. Refluxing was continued until the mixture tested neutral to pHpaper (˜1.5 hrs.). The precipitated sodium bromide was filtered off thecold solution and most of the ethanol was removed on an evaporator. Themixture was filtered again and distilled. The3-ethoxycarbonyl-4-methylhexane-2,4-dione fraction which boiled at131°-137° C./18 mm. was collected.

EXAMPLE 46 3-methyl-hexane-2,5-dione

A mixture of 3.0 g. (0.15 mol) of3-ethoxycarbonyl-4-methyl-hexane-2,4-dione, 30.0 g. (0.217 mol) ofpotassium carbonate and 120 ml. of water was refluxed for 4 hrs. undervigorous stirring (oil-bath temperature 120° C.). The reaction mixturewhich was cold was then diluted with ether, the ether layer separatedand the aqueous phase was extracted again with ether. The combinedorganic phases were washed with sodium chloride solution, dried andevaporated. The residue was distilled under reduced pressure to yield3-methyl-hexane-2,5-dione, b.p. 79°-84° C./18 mm.

EXAMPLE 47 2,3,5-trimethylthiophene

10.6 G. (0.083 mol) of 3-methyl-hexane-2,5-dione was added slowly to 7.4g. (0.033 mol) of phosphorus pentasulfide under stirring and coolingwith an ice bath. The resulting reaction mixture was allowed to warm toroom temperature and then heated slowly under vigorous stirring to65°-70° C. At this temperature, a vigorous reaction took place (hydrogensulfide developement). Heating was discontinued. After 10 min. thereaction had subsided and the mixture was heated showly to 160° C. andkept at this temperature for 3 hrs. with the addition of 1.0 g. ofphosphorus pentasulfide after the first half hour. The liquid wasdistilled away from the tarry residue between 157°-165° C. The crudeproduct was refluxed for 15 min. over about 0.5 g. of sodium and thendistilled to yield 2,3,5-trimethylthiophene, b.p. 85°-89° C./61 mm.

EXAMPLE 48 2,3,4-trimethylthiophene

12.3 G. (0.0385 mol) of 2,3,4-tribromothiophene was dissolved in 1 l. ofdry ether. The resulting solution was cooled to -78° C. and a precooledsolution of 1.0 mol. of n-butyl lithium (2.4 molar) in hexane was addeddropwise. The reaction mixture was stirred for 3 hrs. at -78° C. Afterthe dropwise addition of a precooled solution of 126 g. (1.0 mol. 94.7ml.) of dimethyl sulfate in 300 ml. of ether, stirring was continued at-78° C. for one hour. The reaction mixture then was allowed to warm upto room temperature and a solution of 48 g. (1.2 mol) of sodiumhydroxide in 600 ml. of water was added slowly. After 2 hrs., theresulting layers were separated. The organic phase was washed threetimes with water, dried and evaporated. Distillation of the residue gavetrimethylthiophene, b.p. 67°-69° C./18 mm.

EXAMPLE 49 3,4,5-trimethylthiophene-2-carboxaldehyde

A mixture of 4.32 g. (0.032 mol) of N-methyl-formanilide, 4.90 g. (0.032mol) of phosphorus oxychloride and 4.04 g. (0.032 mol) of2,3,4-trimethylthiophene was warmed briefly on a steam bath untilevolution of hydrogen chloride began. The heat was removed and, ifnecessary, the reaction was moderated by cooling. After stirring at roomtemperature overnight, ice and ether were added and the mixture wasstirred for one hour. The phases were separated and the aqueous layerwas extracted three times with ether. The combined organic phases werewashed twice with 6 N hydrochloric acid, water, sodium bicarbonate andwater, dried and evaporated. The residue was recrystallized from 75%ethanol/water to yield 3,4,5-trimethylthiophene-2-carboxaldehyde, m.p.45°-46° C.

EXAMPLE 50 2-hydroxymethyl-3-methylthiophene

0.95 G. (0.025 mol) of sodium borohydride were added in portions to asolution of 12.6 g. (0.1 mol) of 3-methylthiophene-2-carboxaldehyde in150 ml. of ethanol. The resulting reaction mixture was stirred at roomtemperature for 0.5 hr., poured into ice water and extracted with ether.The organic phase was washed with saturated sodium chloride solution,dried and evaporated. The residue was distilled to yield2-hydroxymethyl-3-methylthiophene, b.p. 46° C./0.3 mm.

EXAMPLE 51 Alltrans-3,7-dimethyl-9-(3-methyl-2-thienyl)-2,4,6,8-nonatetraenoic acidethyl ester

1.16 G. of a 50% suspension in mineral oil, (23 mmol) of sodium hydridewas washed with pentane, dried and suspended in 50 ml. of drydimethylformamide. A suspension of 7.5 g. (16.4 mmol) of(3-methyl-2-thenyl)-triphenylphosphonium bromide in 25 ml. ofdimethylformamide was added dropwise. The resulting reaction mixture wasstirred for 15 minutes. A solution of 3.74 g. (18 mmol) of ethyl7-formyl-3-methyl-2,4,6-octatrienoate in 20 ml. of DMF was added slowly.After stirring for 2.5 hours at room temperature, the reaction mixturewas poured into a methanol/water mixture (ratio 6:4) and extractedseveral times with hexane. The combined organic phases were washed oncewith methanol/water (6:4); dried and evporated. The crude product wasrecrystallized from hexane to yield alltrans-3,7-dimethyl-9-(3-methyl-2-thienyl)-2,4,6,8-nonatetraenoic acidethyl ester.

EXAMPLE 52 2-hydroxymethyl-5-methylthiophene

0.55 G. (15 mmol) of sodium borohydride were added in portions to asolution of 7.0 g. (56.0 mmol) of 5-methylthiophene-2-carboxaldehyde in100 ml. of ethanol. The resulting reaction mixture was stirred at roomtemperature for 0.5 hr., poured into ice water and extracted with ether.The organic phase was washed with saturated sodium chloride solution,dried and evaporated. The residue was distilled to yield2-hydroxymethyl-3-methylthiophene.

EXAMPLE 53 2-chloromethyl-3,4-tribromothiophene

4.07 G. (50 mmol) of formalin (37%) and 40 ml. of concentratedhydrochloric acid were added to a solution of 10.2 g. (33.3 mmol) of3,4,5-tribromothiophene in 20 ml. of acetic acid. The resulting mixturewas warmed to 70° C. After 6 hrs., 4.07 g. of formalin were added andheating was continued overnight. The resulting mixture as cooled, pouredon ice water and extracted with ether. The organic phase was washedtwice with water, sodium bicarbonate and water, dried and evaporated togive crude 2-chloromethyl-3,4,5-tribromothiophene.

EXAMPLE 542,4,6-trans-8-cis-3,7-dimethyl-9-(3,4,5-tribromo-2-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester and alltrans-3,7-dimethyl-9-(3,4-dibromo-2-thienyl)-2,4,6,8-nonatetraenoic acidethyl ester

Sodium hydride (1.04 g. of a 50% suspension in mineral oil, 21.6 mmol)was washed with pentane, dried and suspended in 100 ml. of drydimethylformamide. At 0° C., 13.0 g. (20.6 mmol) of(3,4,5-tribromo-2-thenyl)-triphenyl phosphonium chloride were added insmall portions to the suspension. After stirring for 20 min., a solutionof 4.70 g. (22.6 mmol) of ethyl-7-formyl-3-methyl-2,4,6,-octatrienoatein 30 ml. of dimethylformamide was added slowly. The resulting reactionmixture was stirred at 0°-5° C. for one hour, poured into amethanol/water mixture (ratio 6:4) and extracted several times withhexane. The combined organic phases were washed once with methanol/water(6:4), dried and evaporated. The crystalline crude material whichresulted was filtered through a short column (silica gel, hexane/ethylacetate 4:1). The filtrate was evaporated and separated by preparativehigh pressure liquid chromatography. The two main fractions of theLC-separation were recrystallized from hexane to yield pure2,4,6-trans-8-cis-3,7-dimethyl-9-(3,4,5-tribromo-2-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester, m.p. 84°-86° C., and pure alltrans-3,7-dimethyl-9-(3,4-dibromo-2-thienyl)-2,4,6,8-nonatetraenoic acidethyl ester, m.p. 106°-110° C.

EXAMPLE 55 Alltrans-3,7-dimethyl-9-(3,4,5-tribromo-2-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester

Three crystals of iodine were added to a solution of 2.3 g. (4.38 mmol)of2,4,6-trans-8-cis-3,7-dimethyl-9-(3,4,5-tribromo-2-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester in 100 ml. of benzene and then stirred at roomtemperature overnight. The resulting solution was washed once with 1 Nsodium thiosulfate and water, dried and evaporated. The crude productwas purified by chromatography (silica gel, methylene chloride) to yieldafter recrystallization from 50% hexane/ethyl acetate pure alltrans-3,7-dimethyl-9-(3,4,5-tribromo-2-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester, m.p. 158°-159° C.

EXAMPLE 56 2-methyl-3,4-dibromothiophene

37.6 Ml. (90.2 mmol) of a solution of n-butyl lithium in hexane (22%,2.4 ml.) were slowly added at -78° C. to a solution of 29.0 g. (90.2mmol) of tribromothiophene in 600 ml. of dry ether. The resultingreaction mixture was stirred at -78° C. for 1.5 hrs. 9.0 ml. (95 mmol)of dimethylsulfate were slowly added. After stirring at -78° C. foranother hour, the reaction mixture was allowed to warm up to roomtemperature and was stirred for one hour. A solution of 4.8 g. (0.12mol) of sodium hydroxide in 150 ml. of water was added and the resultingmixture was stirred for two hours at room temperature. The phases wereseparated, the ether layer washed with water, dried and evaporated. Theremaining liquid was quickly distilled and the fraction which boiled at54°-60° C./0.5 mm. was again distilled using a Vigreux-column to yield2-methyl-3,4-dibromothiophene, b.p. 38°-42° C./0.25 mm.

EXAMPLE 57 All trans and2,4,6-trans-8-cis-3,7-dimethyl-9-(3,4-dibromo-5-methyl-2-thienyl)2,4,6,8-nonatetraenoicacid ethyl ester

A suspension of 16.64 g. (29.4 mmol) of phosphonium chloride and 6.72 g.(32.3 mmol) of ethyl-7-formyl-3-methyl-2,4,6-octatrienoate in 300 ml. ofbutylene oxide were heated to 70° C. for 15 hrs. The resulting clearsolution was cooled and the solvent evaporated. The residue wasdissolved in hexane/ethyl acetate (ratio 1:1) and filtered through ashort column (silica gel). The resulting filtrate was evaporated to avolume of about 100 ml. The crystals which precipitated were filteredand recrystallized from hexane/ethyl acetate (1:1) to yield alltrans-2,4,6,8-3,7-dimethyl-9-(3,4-dibromo-5-methyl-2-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester, m.p. 150°-153° C.

Preparative LC of the filtrate yielded after recrystallization fromhexane a mixture of 80%2,4,6-trans-8-cis-3,7-dimethyl-9-(3,4-dibromo-5-methyl-2-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester and 20% of the all-trans isomer m.p. 73°-76° C.

EXAMPLE 58 Alpha-mercapto-acetone

A solution of 48 g. (1.2 mol) of sodium hydroxide in 300 ml. of waterwas cooled to 0° C. and saturated with hydrogen sulfide. Freshlydistilled chloroacetone (105 g., 1.1 mol, b.p. 108°-110° C.) was slowlyadded. During the addition the reaction temperature should not be higherthan 0° C. (acetone/dry ice bath). The reaction mixture was stirred at0° C. for thirty minutes. The resulting white precipitate was filtered,washed well with cold water, alcohol and ether and dried at roomtemperature under high vacuum to yield the dimer ofalpha-mercapto-acetone, m.p. 108°-111° C.

EXAMPLE 59 2,4-dimethyl-2,5-dihydrothiophene

Two ml. of dry triethylamine were added to a suspension of 170 g. (0.44mol) of (allyl)-triphenyl phosphonium bromide in one liter of drypyridine. After one hour of stirring at room temperature, 70 g. (0.68mol) of dry triethylamine were added. Stirring was continued for anadditional thirty minutes. After adding 40 g. (0.44 mol) ofalpha-mercapto-acetone dimer to the resulting yellow clear solution, thereaction mixture was refluxed for 20 hrs. (oil bath 120° C.) underargon. The mixture was cooled, poured into ice water, neutralized with12 N hydrochloric acid and extracted four times with a mixture ofpentane/ether (ratio 1:1). The combined organic phases were washed with3 N hydrochloric acid and sodium chloride solution. The dried solventwas evaporated at normal pressure using a Vigreux-column. The resultingprecipitated triphenylphosphine oxide was filtered, washed well withcold pentane and the filtrate distilled again to yield2,4-dimethyl-2,5-dimethyl-2,5-dihydrothiophene as a colorless liquid,b.p. 101°-103° C./150 mm.

EXAMPLE 60 2,4-dimethylthiophene

A solution of 22.4 g. (0.124 mol) of 2,4-dimethyl-2,5-dihydrothiophenein 100 ml. of dry benzene was heated to reflux and a solution of 51.0 g.(0.225 mol) of DDQ in 1400 ml. of dry benzene was added through adropping funnel. The resulting reaction mixture was heated for anotherhour, then cooled and filtered. The precipitate was washed well withether. The filtrate was washed several times with 5% sodium bicarbonatesolution and dried with sodium sulfate. The solvent was evaporated atnormal pressure using a Vigreux-column. Distillation of the residueyielded 2,4-dimethylthiophene as a colorless liquid, b.p. 98°-101°C./180 mm.

EXAMPLE 61 Alltrans-3,7-dimethyl-9-(2,4-dimethyl-5-chloro-3-thienyl-2,4,6,8-nonatetraenoicacid ethyl ester

A mixture of 6.74 g. (14.7 mmol) of(5-chloro-2,4-dimethyl-3-thenyl)triphenyl phosphonium chloride, 3.15 g.(15.1 mmol) of ethyl 7-formyl-3-methyl-2,4,6-octatrienoate and 300 ml.of butylene oxide was refluxed until the solution became clear (about 22hrs.). The clear solution was cooled, poured into 500 ml. of amethanol/water mixture (ratio 6:4) and extracted with hexane. Thecombined hexane extracts were washed with methanol/water (6:4), driedand evaporated. The resulting crude material was purified bychromatography (silica gel, hexane/ether=4:1) to yield afterrecrystallization from hexane, alltrans-3,7-dimethyl-9-(2,4-dimethyl-5-chloro-3-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester, m.p. 109°-110° C.

EXAMPLE 62 2-methyl-3,5-dichlorothiophene

78.2 G. (0.58 mol) of sulfuryl chloride were slowly added to a solutionof 29.4 g. (0.3 mol) of 2-methylthiophene in 300 ml. of methylenechloride. The resulting reaction mixture was stirred overnight at roomtemperature, poured into ice water and extracted with hexane. The hexanesolution was washed with water, 1 N sodium bicarbonate and water, driedand evaporated. The resulting liquid residue was distilled, b.p. 30°-60°C./0.15 mm. (28.5 g.). According to GC this material contained 68% of2-methyl-3,5-dichlorothiophene. The main side product was2-chloro-5-methylthiophene. A second distillation using a Vigruex columnyielded almost pure 2-methyl-3,5-dichlorothiophene, b.p. 62°-65° C./10mm.

EXAMPLE 63 3-chloromethyl-2,4-dichloro-5-methylthiophene

8.6 G. (0.107 mol) of formalin and 90 ml. of concentrated hydrochloricacid were added to a solution of 10.87 g. (0.065 mol) of2-methyl-3,5-dichlorothiophene in 45 ml. of acetic acid. The resultingmixture was heated to 70° C. for 18 hrs., cooled, poured into ice waterand extracted with ether. The organic solution was washed with water,sodium bicarbonate and water, dried and evaporated to yield3-chloromethyl-2,4-dichloro-5-methylthiophene as a crude oil.

EXAMPLE 64 (2,4-dichloro-5-methyl-3-thenyl)triphenyl phosphoniumchloride

A mixture of 13.1 g. (˜0.061 mol) of crude3-chloromethyl-2,4-dichloro-5-methylethiophene, 26.2 g. (0.10 mol) oftriphenylphosphin and 200 ml. of toluene was warmed to 100° C. for 20hrs., then cooled to room temperature. The resulting precipitate wascollected by filtration, washed with cold benzene and dried at 80° C.under high vacuum to yield (2,4-dichloro-5-methyl-3-thenyl)triphenylphosphonium, m.p. 211°-214° C.

EXAMPLE 65 Alltrans-3,7-dimethyl-9-(2,4-dichloro-5-methyl-3-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester

A suspension of 10.83 g. (22.6 mmol) of(2,4-dichloro-5-methyl-3-thenyl)triphenyl phosphonium chloride and 5.15g. (24.8 mmol) of ethyl 7-formyl-3-methyl-2,4,6-octatrienoate in 350 ml.of butylene oxide was heated to 70° C. for 4.5 hrs. The resulting clearsolution was cooled, poured into 500 ml. of a methanol/water mixture(6:4) and extracted with hexane. The combined hexane extracts werewashed with methanol/water (6:4), dried and evaporated. The resultingcrude material was purified by chromatography (silica gel, hexane/ethylacetate=4:1) to yield after recrystallization from hexane, alltrans-3,7-dimethyl-9-(2,4-dichloro-5-methyl-3-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester, m.p. 99°-100° C.

EXAMPLE 66 2,4-diethoxycarbonyl-3-methyl-5-acetylamino-thiophene

A solution of 23.0 g. (0.09 mol) of2,4-diethoxycarbonyl-3-methyl-5-aminothiophene in 250 ml. of aceticanhydride was heated to 100° C. for 1.5 hrs. The resulting mixture wascooled in an ice bath and the precipitated crystals were filtered toyield 2,4-diethoxycarbonyl-3-methyl-5-acetylamino-thiophene, m.p.130°-131° C.

EXAMPLE 67 2,4-diethoxycarbonyl-3-bromomethyl-5-acetylamino-thiophene

10.5 G. (59 mmol) of N-bromo-succinimide and 20 mg. of benzoylperoxidewere added to a solution of 17.5 g. (59 mmol) of2,4-dethoxycarbonyl-3-methyl-5-acetylamino-thiophene in 250 ml. ofcarbontetrachloride. The resulting mixture was refluxed for 24 hrs.,until all solid material was floating on the surface. After one andseven hours respectively were added 20 mg. of benzoylperoxide. Because aseparation of the product2,4-diethoxycarbonyl-3-bromomethyl-5-acetylaminothiophene andsuccinimide proved to be very difficult, the crude product, anintermediate was used without further purification.

EXAMPLE 68 (2,4-diethoxycarbonyl-5-acetylamino-3-thenyl)-triphenylphosphonium bromide

22.2 G. of crude2,4-diethoxycarbonyl-3-bromomethyl-5-acetylaminothiophene, 19.7 g. (75mmol) of triphenylphosphine and 700 ml. of toluene were refluxed for 3hrs. The resulting precipitate was filtered from the hot solution andwashed well with toluene to yield(2,4-diethoxycarbonyl-5-acetylamino-3-thenyl)triphenyl phosphoniumbromide, m.p. 186°-195° C. The NMR-spectrum showed that the materialcontained 11% of succinimide.

EXAMPLE 69 Alltrans-3,7-dimethyl-9-(2,4-diethoxycarbonyl-5-acetylamino-3-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester

A suspension of 30.0 g. (˜47 mmol, containing 11% of succinimide) of(2,4-diethoxycarbonyl-5-acetylamino-3-thenyl)triphenyl phosphoniumbromide and 9.75 g. (47 mmol) ofethyl-7-formyl-3-methyl-2,4,6-octatrienoate in a mixture of 500 ml. oftoluene and 100 ml. of butylene oxide was refluxed until the solutionwas clear (for three hours). The resulting solution was cooled and thesolvent evaporated. The residue which resulted was suspended in 600 ml.of a methanol/water (ratio 6:4) mixture and one liter of hexane andstirred for 0.5 hr. The insoluble material was filtered and boiled with3 l. of hexane. The insoluble material was filtered from the coldsolution, washed with hexane and purified by chromatography (silicagel), ethyl acetate). Recrystallization of the purer fractions fromhexane/40% ethyl acetate yielded alltrans-3,7-dimethyl-9-(2,4-diethoxycarbonyl-5-acetylamino-3-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester, m.p. 159°-161° C.

EXAMPLE 70 2-hydroxymethyl-3-methyl-5-iodothiophene

6.58 G. (33 mmol) of mercuric oxide and 7.62 g. (30 mmol) of iodine wereadded alternately in small amounts to a vigorously stirred solution of3.84 g. (30 mmol) of 2-hydroxymethyl-3-methylthiophene in 30 ml. ofbenzene. The reaction was kept at room temperature by cooling with anice bath. The orange mercuric iodide which precipitated was filtered andwashed well with benzene. The combined organic solutions were washedwith sodium thiosulfate and saturated sodium chloride solution, driedand evaporated to yield crude 2-hydroxymethyl-3-methyl-5-iodothiopheneas a colorless oil.

EXAMPLE 71 2-hydroxymethyl-3-methyl-5-methoxythiophene

10.0 G. (0.125 mol) of cupric oxide and 11.0 g. (0.0433 mol) of2-hydroxymethyl-3-methyl-5-iodothiophene was added to a solution of 10.0g. (0.435 mol) of sodium in 90 ml. of methanol. The resulting reactionmixture was heated to 80° C. for 18 hrs. with vigorous stirring. Thecold solution was filtered, the filtrate poured into ice water andextracted with ether/hexane (ratio 4:1). The organic extracts werewashed with 10% sodium thiosulfate solution and saturated sodiumchloride solution, dried and evaporated to yield2-hydroxymethyl-3-methyl-5-methoxythiophene as a colorless oil.

EXAMPLE 72 (3-methyl-5-methoxy-2-thenyl)triphenylphosphonium chloride

21.0 G. (80.2 mmol) of triphenylphosphine were added to a solution of5.8 g. (36.7 mmol) of 2-hydroxymethyl-3-methyl-5-methoxythiophene in 60ml. of dry carbon tetrachloride and 80 ml. of toluene. The temperatureof the reaction mixture was slowly raised to 80° C. and heating wascontinued overnight. The resulting precipitate was filtered from thecold solution, washed well with cold benzene and dried in high vacuum toyield (3-methyl-5-methoxy-2-thenyl)triphenyl phosphonium chloride, m.p.180°-185° C.

EXAMPLE 73 Alltrans-3,7-dimethyl-9-(3-methyl-5-methoxy-2-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester

A suspension of 5.9 g. (13.5 mmol) of(3-methyl-5-methoxy-2-thenyl)triphenyl phosphonium chloride and 2.81 g.(13.5 mmol) of ethyl-7-formyl-3-mehtyl-2,4,6-octatrienoate in 70 ml. ofbutylene oxide and 200 ml. of toluene was heated to 100° C. for 14 hrs.The resulting clear solution was cooled, poured into 500 ml. of amethanol/water mixture (6:4) and extracted with hexane. The combinedhexane extracts were washed with methanol/water (6:4), dried andevaporated. The resulting crude, oily material was purified bychromatography (silica gel, hexane/ether, ratio 7:3) to yield afterrecrystallization from hexane alltrans-3,7-dimethyl-9-(3-methyl-5-methoxy-2-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester, m.p. 66°-72° C.

EXAMPLE 74 2,4-dimethyl-3,5-dibromothiophene

A solution of 47.36 g. (0.296 mol) of bromine in 500 ml. of dioxane wasslowly added to a solution of 16.58 g. (0.148 mol) of2,4-dimethylthiophene in 150 ml. of dioxane. The reaction mixture waskept at room temperature and stirring was continued for 18 hrs. Thereaction mixture then was poured into ice water and extracted withether. The combined organic layers were washed with 5% sodium carbonateand saturated sodium chloride solution, dried and evaporated using aVigreux column. Distillation of the residue gave two fractions, b.p.75°-79° C./0.3 mm. and b.p. 80°-81° C./0.2 mm. According to GC, fraction1 was 89% pure, fraction 2 95% pure. The fractions were combined toyield 3,5-dibromo-2,4-dimethylthiophene.

EXAMPLE 75 2,4-dimethyl-3-bromothiophene

A solution of 36.0 g. (0.133 mol) of 2,4-dimethyl-3,5-dibromothiophenein 250 ml. of dry ether was cooled to -68° C. and 60 ml. of a hexanesolution of n-butyl lithium (2.4 molar, 0.144 mol) were added dropwise.The reaction mixture was allowed to warm up to -32° C. for 15 min.,cooled again to -70° C. and then quenched by adding 50 ml. of water. Theresulting mixture was stirred for ten minutes, poured into ice water andextracted with ether/hexane (ratio 4:1). The combined organic layerswere washed with 5% sodium carbonate and saturated sodium chloridesolution, dried and evaporated using a Vigreux column. Distillation ofthe residue yielded 2,4-dimethyl-3-bromothiophene, b.p. 50°-51° C./10mm.

EXAMPLE 76 2,4-dimethylthiophene-3-carboxaldehyde

A solution of 15 g. (79.0 mmol) of 2,4-dimethyl-3-bromothiophene in 120ml. of dry ether was cooled to -70° C. and 36 ml. of a hexane solutionof n-butyl lithium (2.4 molar, 86.4 mmol) were added dropwise. Thereaction mixture was allowed to warm up to -20° C. for 10 min., cooledagain to -70° C. and then quenched by adding dropwise 15 g. (0.205 mol)of dimethylformamide. The mixture was stirred at room temperatureovernight, poured into ice water, stirred for 15 min. and extracted fourtimes with ether. The ether phase was washed with saturated sodiumchloride solution, dried and evaporated. The resulting oily residue wasdistilled to yield 2,4-dimethylthiophene-3-carboxaldehyde, b.p. 50°-55°C./0.1 mm.

EXAMPLE 77 2,4-dimethyl-3-hydroxymethylthiophene

0.68 G. (18 mmol) of sodium borohydride was added in three portions to asolution of 10.08 g. (72 mmol) of 2,4-dimethylthiophene-3-carboxaldehydein 120 ml. of ethanol. After 15 min., the reaction mixture was pouredinto water, extracted with ether, dried and the solvent evaporated. Theresulting residue was recrystallized from hexane to yield2,4-dimethyl-3-hydroxymethylthiophene, m.p. 80°-81° C.

EXAMPLE 78 2,4-dimethyl-3-hydroxymethyl-5-iodothiophene

10.0 G. (46 mmol) of mercuric oxide and 14.7 g. (58 mmol) of iodine wereadded alternately over a period of 11/4 hrs. to a vigorously stirredsolution of 8.2 g. (57.7 mmol) of 2,4-dimethyl-3-hydroxymethylthiophenein 300 ml. of benzene. The reaction mixture was kept at room temperatureby cooling with an ice bath and stirring was continued for an additionalhour. The mercuric iodide which precipitated was filtered and washedwell with warm ethyl ether. The combined organic solutions were washedwith 10% sodium thiosulfate and saturated sodium chloride solution,dried and evaporated. The resulting residue was dissolved in a minimumamount of hot ether, an equal amount of hexane was added and thesolution cooled to -50° C. The crystals which precipitated were filteredand washed with cold hexane to yield after drying2,4-dimethyl-3-hydroxymethyl-5-iodothiophene, m.p. 118.5°-120.5° C.

EXAMPLE 79 2,4-dimethyl-3-hydroxymethyl-5-methoxythiophene

12.0 G. (0.151 mol) of cupric oxide and 12.5 g. (0.0466 mol) of2,4-dimethyl-3-hydroxymethyl-5-iodothiophene were added to a solution of12.5 g. (0.543 mol) of sodium in 100 ml. of dry methanol. The reactionmixture was heated to 80°-82° C. (internal temperature) for 20 hrs. withvigorous stirring, then cooled. The cold solution was diluted with 150ml. of methanol, filtered, poured into ice water and extracted withether/hexane (ratio 4:1). The organic layers were washed with 5% sodiumcarbonate solution, dried and evaporated. The residue which resulted wasrecrystallized from hexane to yield2,4-dimethyl-3-hydroxymethyl-5-methoxythiophene, m.p. 55°-60° C. Thisproduct contained about 10% of 2,4-dimethyl-3-hydroxymethylthiophenewhich is formed in this reaction by reduction of the iodide. Fractionrecrystallization of a sample from hexane yielded pure2,4-dimethyl-3-hydroxymethyl-5-methylthiophene, m.p. 64°-65° C.

EXAMPLE 80 (2,4-dimethyl-5 -methoxy-3-thenyl)-triphenylphosphoniumbromide

6.1 G. (35.5 mmol) of 2,4-dimethyl-3-hydroxymethyl-5-methoxythiophenewere added at 35° C. with vigorous stirring to a suspension of 13.4 g.(39.0 mmol) of triphenylphosphonium bromide in 250 ml. of acetonitrile.The deep purple color which was formed immediately, disappeared aftersome minutes. The reaction mixture was stirred for 3 hrs. The solventwas evaporated to a volume of about 25 ml. and an excess of cold etherwas added. The solvent then was decanted from the resulting oilyprecipitate which was dissolved in warm acetone and again precipitatedby adding cold ether. The solvent was decanted and the resulting oilyresidue was dried in high vacuum to yield(2,4-dimethyl-5-methoxy-3-thenyl)-triphenylphosphonium bromide.

EXAMPLE 81 Alltrans-3,7-dimethyl-9-(2,4-dimethyl-5-methoxy-3-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester

A suspension of 11.0 g. (22.1 mmol) of2,4-dimethyl-5-methoxy-3-thenyl)triphenyl phosphonium bromide and 5.1 g.(24.5 mmol) of ethyl-7-formyl-3-methyl-2,4,6-octatrienoate in 450 ml. ofbutylene oxide was heated to 70° C. until a clear solution resulted(about 12 hours). The resulting clear solution was cooled, poured into500 ml. of methanol/water (6:4) and extracted with hexane. The combinedhexane extracts were washed with methanol/water (6:4) dried andevaporated. The resulting crude material was purified by columnchromatography (silica gel, hexane/ether=10:3) to yield afterrecrystallization from hexane, alltrans-3,7-dimethyl-9-(2,4-dimethyl-5-methoxy-3-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester, m.p. 81°-82° C.

EXAMPLE 82 4-bromo-3,5-dimethylthiophene-2-carboxaldehyde

15.0 G. of 2,4-dibromo-3,5-dimethylthiophene was dissolved in 250 ml. ofanhydrous ether and cooled to -70° C. with stirring under argon. 24 Ml.of a 2.4 M solution of n-butyl lithium was slowly added to the solutionand the mixture was warmed to -35° C. for 10 minutes, and then cooledagain to -70° C. 7.3 G. of dimethylformamide was added slowly to themixture and the reaction mixture was warmed to room temperature for 14hours. The resulting solution was poured into ice water, stirred for 20minutes and extracted with ethyl ether. The ether extracts werecombined, washed with an aqueous solution of 5% sodium carbonate,saturated sodium chloride solution, dried with sodium sulfate, filteredand evaporated to yield 4-bromo-3,5-dimethylthiophene-2-carboxaldehyde,m.p. 44°-45° C.

EXAMPLE 83 4-bromo-3,5-dimethyl-2-hydroxymethylthiophene

11.8 G. of 4-bromo-3,5-dimethylthiophene-2-carboxaldehyde was dissolvedin 250 ml. of dry ethanol and stirred at 20° C. 0.52 G. of sodiumborohydride was added and the resulting solution was stirred for 30minutes, then poured into ice water and extracted with ethyl ether. Thecombined ether extracts were washed with a solution of 5% sodiumcarbonate and a saturated sodium chloride solution, dried over sodiumsulfate, filtered and evaporated. Crystallization from cold hexaneyielded 4-bromo-3,5-dimethyl-2-hydroxymethylthiophene, m.p. 85°-90° C.

EXAMPLE 84 4-bromo-3,5-dimethyl-2-methoxymethylthiophene

2.9 G. of a 50% suspension of sodium hydride in mineral oil was washedonce with pentane and suspended in 100 ml. of dimethylformamide at 5° C.10.5 G. of a solution of 4-bromo-3,5-dimethyl-2-hydroxymethylthiophenein 40 ml. of dimethylformamide was added slowly to the suspension andstirred for 30 minutes. 10 G. of methyl iodide was added and theresulting mixture was stirred for 14 hours at 20° C. The reactionmixture was then poured into water and extracted with hexane. The hexaneextracts were washed with a solution of 5% sodium carbonate, a saturatedsolution of sodium chloride, dried over sodium sulfate, filtered andevaporated to yield 4-bromo-3,5-dimethyl-2-methoxymethylthiophene.

EXAMPLE 85 2,4-dimethyl-5-methoxymethylthiophene-3-carboxaldehyde

15.5 G. of 4-bromo-3,5-dimethyl-2-methoxymethylthiophene was dissolvedin 200 ml. of anhydrous ethyl ether under argon. The resulting solutionwas cooled to -70° C. and 22 ml. of a 2.4 M solution of n-butyl lithiumwas slowly added. The reaction mixture was warmed to -30° C. for 10minutes and then cooled to -70° C. 7.3 G. of dimethylformamide wasslowly added and the reaction was warmed to room temperature for 14hours. The resulting reaction mixture was poured into ice water, stirredfor 15 minutes and extracted with ethyl ether. The combined etherextracts were washed with a solution of 5% sodium carbonate, a saturatedsolution of sodium chloride, dried over sodium sulfate, filtered andevaporated to yield2,4-dimethyl-5-methoxymethylthiophene-3-carboxaldehyde.

EXAMPLE 86Ethyl-3,7-dimethyl-9-(2,4-dimethyl-5-methoxymethyl-3-thienyl)-2,4,6,8-nonatetraenoate

3.6 G. of a 50% suspension of sodium hydride in mineral oil was washedonce with pentane, and suspended in 200 ml. of dimethylformamide at 5°C. 40.2 G. of a solution oftriphenyl-(7-ethoxycarbonyl-2,6-dimethyl-2,4,6-heptatrienyl)phosphoniumbromide in 75 ml. of dimethylformamide was added slowly and stirred for30 minutes. 12.6 G. of a solution of2,4-dimethyl-5-methoxymethylthiophene-3-carboxaldehyde in 50 ml. ofdimethylformamide was then added slowly. The resulting reaction mixturewas stirred at 5° C. for 10 hours, poured into ice water and extractedwith hexane. The hexane extracts were combined and washed twice with amethanol/water mixture (ratio 6:4) and once with a solution of saturatedsodium chloride, dried over sodium sulfate, filtered and evaporated. Thecrude material was purified by column chromatography on silica gel andelution with ethyl ether/hexane (1:3) to yield ethyl cis andtrans-3,7-dimethyl-9-(2,4-dimethyl-5-methoxymethyl-3-thienyl)-2,4,6,8-nonatetraenoate.

EXAMPLE 87 (2,4-dimethyl-3-thenyl)triphenylphosphonium bromide

4.4 G of 2,4-dimethyl-3-hydroxymethylthiophene and 10.7 g. oftriphenylphosphonium bromide were dissolved in 40 ml. of acetonitrileand stirred at 40° C. for 1 hour. The resulting solution was cooled and150 ml. of ethyl ether was added. The white precipitate which formed wasfiltered and washed with cold acetone to yield(2,4-dimethyl-3-thenyl)triphenylphosphonium bromide, m.p. 262°-265° C.

EXAMPLE 88 Ethyl alltrans-3,7-dimethyl-9-(2,4-dimethyl-3-thienyl)-2,4,6,8-nonatetraenoate

1.35 G. of a 50% suspension of sodium hydride in mineral oil was washedonce with hexane and suspended in 120 ml. of dimethylformamide. At 0°C., 12.0 g of a suspension of(2,4-dimethyl-3-thenyl)triphenylphosphonium bromide in 20 ml. ofdimethylformamide was dropped in and stirred for 30 minutes. 5.8 G. of asolution of 3-methyl-7-formyl-octa-2,4,6-trienoic acid ethyl ester in 30ml. of dimethylformamide then was added dropwise. After stirring at 0°C. for 2 hours, the reaction mixture was poured into ice water andextracted several times with hexane. The combined hexane extracts werewashed twice with a methanol/water mixture (ratio 6:4), once with asaturated sodium chloride solution, dried over sodium sulfate, filteredand evaporated. The resulting crude product was purified by columnchromatography on silica gel and elution with ethyl ether/hexane (1:4).Recrystallization from hexane yielded ethyl alltrans-3,7-dimethyl-9-(2,4-dimethyl-3-thienyl)-2,4,6,8-nonatetraenoate,m.p. 69°-71° C.

EXAMPLE 89 3-bromo-2,4-dimethyl-5-(methylthio)thiophene

20.0 G. of 2,4-dibromo-3,5-dimethylthiophene was dissolved in 300 ml. ofanhydrous ethyl ether. The resulting solution was cooled to -70° C. withstirring under argon. 32 Ml. of a 2.4 M solution of n-butyl lithium wasadded slowly and the solution was warmed to -32° C. for 10 minutes andthen cooled again to -70° C. 7.5 G. of dimethyl disulfide was addedslowly while the temperature was maintained at -70° C. The resultingsolution was warmed to room temperature and stirred for 2 hours thnepoured into ice water, stirred for 15 minutes, and extracted with ethylether. The combined ether extracts were washed with water, 5% sodiumcarbonate, and saturated sodium chloride solution; dried over sodiumsulfate, filtered and evaporated to yield3-bromo-2,4-dimethyl-5-(methylthio)thiophene.

EXAMPLE 90 2,4-dimethyl-5-(methylthio)thiophene-3-carboxaldehyde

18.5 G. of 3-bromo-2,4-dimethyl-5-(methylthio)thiophene was dissolved in250 ml. of anhydrous ethyl ether and cooled to -70° C. with stirringunder argon. 34 Ml. of a 2.4 M solution of n-butyl lithium was addedslowly and the solution was warmed to -25° C. for 10 minutes. Thereaction mixture was again cooled to -70° C. and 7.3 g. ofdimethylformamide was added slowly. The reaction mixture was stirred atroom temperature for 2 hours, poured into ice water, stirred for 15minutes, and finally extracted with ethyl ether. The combined etherextracts were washed with water, a 5% solution of sodium carbonate,saturated sodium chloride solution, dried over sodium sulfate, filtered,and evaporated to yield2,4-dimethyl-5-(methylthio)thiophene-3-carboxyaldehyde.

EXAMPLE 91 2,4-dimethyl-3-hydroxymethyl-5-(methylthio)thiophene

15.0 G. of 2,4-dimethyl-5-(methylthio)thiophene-3-carboxaldehyde wasdissolved in 150 ml. fo dry ethanol with stirring at 20° C. 0.8 G. ofsodium borohydride was added and the mixture was stirred for 30 minutes,then poured into ice water and extracted with ethyl ether. The combinedether extracts were washed with a solution of 5% sodium carbonate andsaturated sodium chloride solution, dried over sodium sulfate, filtered,and evaporated to yield2,4-dimethyl-3-hydroxymethyl-5-(methylthio)thiophene.

EXAMPLE 92 [2,4-dimethyl-5-(methylthio)-3-thenyl]triphenylphosphoniumbromide

14.0 G. of 2,4-dimethyl-3-hydroxymethyl-5-(methylthio)thiophene and 26.0G. of triphenylphosphonium bromide were dissolved in 75 ml. ofacetonitrile and stirred at 40° C. for 1 hour. The resulting mixture wascooled and poured into 150 ml. of ethyl acetate then treated with ethylether/hexane (5:1). The resulting solution was decanted from a gum-likeresidue. The residue was treated with hot acetone and the resultingwhite crystals were filtered, washed with cold acetone and dried underhigh vacuum at 80° C. to yield[2,4-dimethyl-5-(methylthio)-3-thenyl]triphenylphosphonium bromide, m.p.245°-248° C.

EXAMPLE 93 Ethyl alltrans-3,7-dimethyl-9-[2,4-dimethyl-5-(methylthio)-3-thienyl]-2,4,6,8-nonatetraenoate

1.40 G. of a 50% suspension of sodium hydride in mineral oil was washedonce with pentane and suspended in 120 ml. of dimethylformamide. At 0°C., 14.5 g. of a suspension of[2,4-dimethyl-5-(methylthio)-3-thenyl]triphenylphosphonium bromide in 30ml. of dimethylformamide was added dropwise and stirred for 30 minutes.6.5 G. of a solution of 3-methyl-7-formyl-octa-2,4,6-trienoic acid ethylester in 30 ml. of dimethylformamide was then added dropwise. Afterstirring at 0° C. for 2 hours, the reaction mixture was poured into icewater and extracted several times with hexane. The combined hexaneextracts were washed twice with methanol/water (6:4), once with asolution of saturated sodium chloride, dried over sodium sulfate,filtered, and evaporated. The resulting crude product was purified bycolumn chromatography on silica gel and elution with ethyl ether/hexane(1:4). Recrystallization from ethyl ether/hexane (1:9) yielded ethyl alltrans-3,7-dimethyl-9-[2,4-dimethyl-5-(methylthio)-3-thienyl]-2,4,6,8-nonatetraenoate,m.p. 76°-78° C.

EXAMPLE 94 Ethyl3,7-dimethyl-9-(3-methyl-5-nitro-2-thienyl)-2,4,6,8-nonatetraenoate

3.7 G. of a 50% suspension of sodium hydride in mineral oil was washedonce with pentane, and suspended in 450 ml. of dimethylformamide. At 0°C., 42.8 g. of a solution oftriphenyl-(7-ethoxycarbonyl-2,6-dimethyl-2,4,6-heptatrienyl)-phosphoniumbromide in 200 ml. of dimethylformamide was added slowly and stirred for45 minutes. This reaction mixture was added slowly to a cold (0° C.)solution of 3-methyl-5-nitrothiophene-2-carboxaldehyde in 350 ml. ofdimethylformamide under argon. The reaction mixture then was stirred at5° C. for 2 hours, poured into ice water and extracted with ethyl ether.The ether extracts were combined, washed twice with water, dried oversodium sulfate, filtered and evaporated. The resulting crude solid wasdissolved in 600 ml. of ethyl acetate and diluted with 4 liters ofhexane. This was washed three times with a water/methanol mixture (ratio4:6) and the washings were extracted twice with hexane. All organicextracts were combined, washed once with a water/methanol mixture (ratio4:6), once with a solution of saturated sodium chloride, dried oversodium sulfate, filtered and evaporated to yield ethyl cis andtrans-3,7-dimethyl-9-(3-methyl-5-nitro-2-thienyl)-2,4,6,8-nonatetraenoate.

EXAMPLE 95 2,4-diethyl-5-methyl-thiophene

18.2 G. of 2,4-diacetyl-5-methyl-thiophene and 40 ml. of hydrazine(95%+) were dissolved in 160 ml. of diethylene glycol. The resultingsolution was heated to the reflux for 1 hour during which 4.0 ml. ofdistillate was collected. 50 Ml. of diethylene glycol then was added andafter refluxing and additional hour, 4.0 ml. more of distillate wascollected. The reaction mixture was then refluxed at 160° C. for 2.5hours, and cooled to below 80° C. 50 G. of potassium hydroxide then wasadded with stirring and the resulting mixture was carefully warmed to120° C., heated to reflux for 20 minutes and finally distilled until nofurther distillate was collected at 210° C. The resulting distillate wascooled and poured into 500 ml. of ice cold 2 N hydrochloric acid. Theresulting product was extracted several times with diethyl ether. Thecombined organic phases were washed with water, sodium bicarbonatesolution and water, dried over sodium sulfate, filtered and evaporated.The resulting crude product was purified by distillation to yield2,4-diethyl-5-emthyl-thiophene, m.p. 85°-87° C. (20 mm).

EXAMPLE 96 2,4-diethyl-5-methyl-3-chloromethylthiophene

15.0 G. of 2,4-diethyl-5-methylethiophene, 65 ml. of acetic acid, 130ml. of 12 N hydrochloric acid and 8.9 g. of formaldehyde (37% solution)were heated at 70° C. for 2.5 hours. The resulting reaction mixture wascooled, poured into 600 ml. of water and extracted several times withdiethyl ether. The combined organic phases were washed with water,sodium bicarbonate solution and water, dried over sodium sulfate,filtered and evaporated to yield2,4-diethyl-5-methyl-3-chloromethylthiophene.

EXAMPLE 97 (2,4-diethyl-5-methyl-3-thenyl)triphenylphosphonium chloride

19.7 G. of 2,4-diethyl-5-methyl-3-chloromethylthiophene and 39.5 g. oftriphenylphosphine were dissolved in 400 ml. of toluene. The resultingsolution was heated at 115° C. overnight under argon and then cooled toroom temperature. The white phosphonium salt which precipitated wascollected by filtration, washed with toluene and dried at 100° C. underhigh vacuum to yield (2,4-diethyl-5-methyl-3-thenyl)triphenylphosphoniumchloride, m.p. 192°-194° C.

EXAMPLE 98 Alltrans-3,7-dimethyl-9-(2,4-diethyl-5-methyl-3-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester

27.0 G. of (2,4-diethyl-5-methyl-3-thenyl)triphenyl phosphonium chloridewas suspended in 400 ml. of butylene oxide and 13.3 g. of3-methyl-7-formyl-octa-2,4,6-trienoic acid ethyl ester were added. Theresulting mixture was refluxed under argon for 3 hours after which thesolvent was evaporated. The resulting residue was diluted with a mixtureof methanol/water (6:4) and extracted several times with hexane. Thecombined organic phases were washed once with methanol/water (6:4),dried over sodium sulfate, filtered and evaporated. The resulting crudeproduct was purified by column chromatography (hexane/5% ethyl acetate).Two recrystallizations from hexane yielded alltrans-3,7-dimethyl-9-(2,4-diethyl-5-methyl-3-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester, m.p. 79°-80° C.

EXAMPLE 99 (3-thenyl)triphenylphosphonium bromide

34.3 G. of 3-bromomethyl-thiophene and 61.0 g. of triphenylphosphinewere dissolved in 500 ml. of benzene. The resulting mixture was refluxedovernight under argon and then cooled to room temperature. The tanphosphonium salt which precipitated was collected by filtration, washedseveral times with toluene and dried at 100° C. under high vacuum toyield (3-thenyl)triphenylphosphonium bromide, m.p. >270° C.

EXAMPLE 1002,4,6-trans-8-cis-3,7-dimethyl-9-(3-thienyl)-2,4,6,8-nonatetraenoic acidethyl ester

22.5 G. of (3-thenyl)triphenylphosphonium bromide was suspended in 200ml. dimethylformamide and cooled to 0°-5° C. 2.4 G. of a 50% suspensionof sodium hydride in mineral oil was added in portions. After stirringfor 30 minutes, a solution of 11.4 g. of3-methyl-7-formyl-octa-2,4,6-trienoic acid ethyl ester in 45 ml. ofdimethylformamide was added dropwise. After stirring for 3 hours at0°-5° C., the reaction mixture was poured into 1000 ml. of water andextracted several times with ethyl acetate. The combined organic phaseswere washed twice with water, dried over sodium sulfate, filtered andevaporated. The resulting crude product was purified by columnchromatography (hexane/10% ethyl acetate). Recrystallizations fromhexane/15% ethyl acetate and hexane yielded2,4,6-trans-8-cis-3,7-dimethyl-9-(3-thienyl)-2,4,6,8-nonatetraenoic acidethyl ester, m.p. 59.5°-60° C.

EXAMPLE 101 All trans-3,7-dimethyl-9-(3-thienyl)-2,4,6,8,-nonatetraenoicacid ethyl ester

26.6 G. of (3-thenyl)triphenylphosphonium bromide was suspended in 200ml. of dimethylformamide and the mixture was cooled to 0°-5° C. 2.90 G.of a 50% suspension of sodium hydride in mineral oil was added inportions. After stirring for 1 hour, a solution of 13.7 g. of3-methyl-7-formyl-octa-2,4,6-trienoic acid ethyl ester was addeddropwise. After stirring for 2 hours at 0°-5° C., the reaction mixturewas poured into 1000 ml. of water and extracted several times with ethylacetate. The combined organic phases were washed twice with water, driedover sodium sulfate, filtered and evaporated. The resulting crudeproduct was purified by column chromatography (hexane/25% ethylacetate). Recrystallization once from hexane/25% ethyl acetate andrepeatedly from hexane/ether yielded alltrans-3,7-dimethyl-9-(3-thienyl)-2,4,6,8-nonatetraenoic acid ethylester, m.p. 99°-101° C.

EXAMPLE 102 3-chloromethyl-2,5-dichloro-4-methylthiophene

A mixture of 61.59 g. (0.368 mol) of 2,5-dichloro-3-methylthiophene,13.1 g. of paraformaldehyde and 3.1 g. of zinc chloride was heated to55° C. Hydrogen chloride gas was passed through the mixture for 7.25hours. The resulting mixture was cooled and poured into a mixture ofether and ice water. The organic phase was separated and washed withsodium chloride solution, sodium bicarbonate solution and sodiumchloride solution again. Evaporation of the dried solvent gave a darkbrown oil which was distilled under reduced pressure to yield3-chloromethyl-2,5-dichloro-4-methylthiophene as a pale yellow liquid,b.p. 87°-92° C./0.75 mm.

EXAMPLE 103 (2,5-dichloro-4-methyl-3-thenyl)triphenylphosphoniumchloride

A mixture of 25.4 g. (0.12 mol) of3-chloromethyl-2,5-dichloro-4-methylthiophene, 34.6 g. (0.132 mol) oftriphenylphosphine and 200 ml. of benzene was heated to the refluxovernight. The resulting beige solid was filtered to yield(2,5-dichloro-4-methyl-3-thenyl)-triphenylphosphonium chloride, m.p.238°-240° C.

EXAMPLE 104 Ethyl alltrans-3,7-dimethyl-9-(2,5-dichloro-4-methyl-3-thienyl)nona-2,4,6,8-tetraenoate

12.3 Ml. of n-butyl lithium (2.45 M in hexane) was added slowly to acold (-10° C.) suspension of 14.6 g. (30.1 mmol) of(2,5-dichloro-4-methyl-3-thenyl)triphenylphosphonium chloride in 200 ml.of ether. The resulting reaction mixture was stirred for 10 minutes. Asolution of 6.27 g. (30.1 mmol) of 3-methyl-7-formylocta-2,4,6-trienoicacid ethyl ester in 100 ml. of ether then was added at -10° C. Thereaction mixture was allowed to warm slowly to room temperature over a2-hour period then was poured into ice water and extracted with ether.The ether extracts were washed with saturated sodium chloride solution,dried with sodium sulfate and evaporated to yield a yellow oil which wastriturated several times with hexane and filtered. The hexane extractswere concentrated and the resulting residue was purified bychromatography on silica gel. Elution with hexane containing 1% etheryielded a yellow oil which crystallized. Repeated crystallization frompentane yielded ethyl alltrans-3,7-dimethyl-9-(2,5-dichloro-4-methyl-3-thienyl)-nona-2,4,6,8-tetraenoateas yellow crystals, m.p. 77°-83° C.

EXAMPLE 105 Alltrans-3,7-dimethyl-9-(2,4,5-trimethyl-3-thienyl)-2,4,6,8-nonatetraen-1-ol

10.0 G. of alltrans-3,7-dimethyl-9-(2,4,5-trimethyl-3-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester was dissolved in 200 ml. of toluene and cooled to -78°C. Di-isobutylaluminum hydride (55.5 ml. of a 25% solution in hexane)was added slowly to the resulting mixture. After stirring at -78° C. for30 minutes the reaction mixture was warmed to 0° C. and 200 ml. of 50%aqueous methanol solution was added slowly. The resulting reactionmixture was filtered and the filter cake was washed with diethyl ether.The filtrate was extracted several times with diethyl ether. Thecombined organic phases were washed twice with water, dried overmagnesium sulfate, filtered and evaporated to yield alltrans-3,7-dimethyl-9-(2,4,5-trimethyl-3-thienyl)-2,4,6,8-nonatetraen-1-ol.

EXAMPLE 106 Alltrans-3,7-dimethyl-9-(2,4,5-trimethyl-3-thienyl)-1-methoxy-2,4,6,8-nonatetraene

1.056 G. of a 50% suspension of sodium hydride in mineral oil wassuspended in 100 ml. of dimethylformamide. 5.76 G. of alltrans-3,7-dimethyl-9-(2,4,5-trimethyl-3-thineyl)-2,4,6,8-nonatetraen-1-olthen was added. The resulting reaction mixture was stirred for 5 minutesand then 3.75 ml. of methyl iodide were added with cooling. Afterstirring at room temperature for about 20 hours the reaction mixture waspoured into 200 ml. of water and extracted several times with ethylacetate. The combined organic phases were washed with water, dried overmagnesium sulfate, filtered and evaporated. The resulting crude productwas purified by column chromatography (hexane/25% ethyl acetate).Recrystallization from methanol yielded alltrans-3,7-dimethyl-9-(2,4,5-trimethyl-3-thienyl)-1-methoxy-2,4,6,8-nonatetraene,m.p. 93°-94° C.

EXAMPLE 107 Alltrans-3,7-dimethyl-9-(2,4,5-trimethyl-3-thienyl)-2,4,6,8-nonatetraen-1-al

5.1 G. of alltrans-3,7-dimethyl-9-(2,4,5-trimethyl-3-thienyl)-2,4,6,8-nonatetraen-1-olwas dissolved in 100 ml. of methylene chloride, which had beenpreviously purified by passing through a column of neutral alumina, and26.1 g. of manganese dioxide were added. After stirring for 20 hours atroom temperature, the reaction mixture was filtered through Celite andevaporated. The resulting crude product was purified by columnchromatography (hexane/25% ethyl acetate). Two recrystallizations fromhexane/25% ethyl acetate yields alltrans-3,7-dimethyl-9-(2,4,5-trimethyl-3-thienyl)-2,4,6,8-nonatetraen-1-al,m.p. 109°-110° C.

EXAMPLE 108 Alltrans-3,7-dimethyl-9-(2,4,5-trimethyl-3-thienyl)-2,4,6,8-nonatetraenamide

6.04 G. of alltrans-3,7-dimethyl-9-(2,4,5-trimethyl-3-thienyl)-2,4,6,8-nonatetraenoicacid was suspended in 100 ml. of toluene. 3.48 Ml. was dropped into thesuspension at room temperature. After stirring for about 20 hours, theacid had dissolved and a red solution of the acid chlorine resulted. Thetoluene then was evaporated and the acid chloride was dissolved in 150ml. of anhydrous liquid ammonia. The resulting mixture was stirred atlow temperature for 3 hours, and then at room temperature for 18 hours.The resulting reaction mixture was diluted with methylene chloride,poured into water and extracted several times with methylene chloride.The combined organic phases were washed once with saturated sodiumchloride solution, dried over magnesium sulfate, filtered andevaporated. Two recrystallizations from 95% ethanol yielded alltrans-3,7-dimethyl-9-(2,4,5-trimethyl-3-thienyl)-2,4,6,8-nonatetraenamide,m.p. 198°-203° C.

We claim:
 1. A compound represented by the formula ##STR23## wherein oneof R₁ or R₂ is ##STR24## and the other of R₁ or R₂ and R₃ and R₄ arehydrogen, lower alkoxy-lower alkyl, hydroxy methyl, halogen, loweralkyl, lower alkoxy, amino, carboxyl, mono(lower alkyl)amino, loweralkyl thio, di(lower alkyl)amino, mono(lower alkyl)amino lower alkyl,di(lower alkyl)amino lower alkyl, hydroxy, lower alkenyl, loweralkenoxy, lower alkanoyl, lower alkanoyloxy, nitro, loweralkoxycarbonyl, lower alkanoylamido or a nitrogen containingheterocycle, selected from the group consisting of piperidino,morpholino, thiomorpholino and pyrrolidino and R₅ is formyl,hydroxymethyl, alkoxymethyl, alkanoyloxymethyl, alkoxycarbonyl,aroyloxymethyl or an N-heterocyclylcarbonyl selected from the groupconsisting of piperidino, morpholino, thiomorpholino and pyrrolidino;with the proviso that when R₅ is alkoxycarbonyl, at least one of R₁, R₂,R₃ and R₄ is lower alkoxy-lower alkyl, hydroxy methyl, halogen, loweralkoxy, amino, carboxyl, mono(lower alkyl)amino, lower alkyl thio,di(lower alkyl)amino, mono(lower alkyl)amino lower alkyl, di(loweralkyl)amino lower alkyl, hydroxy, lower alkenyl, lower alkenoxy, loweralkanoyl, lower alkanoyloxy, lower alkoxycarbonyl, lower alkanoylamidoor a nitrogen containing heterocycle, selected from the group consistingof piperidino, morpholino, thiomorpholino and pyrrolidino.
 2. Thecompound according to claim 1, alltrans-3,7-dimethyl-9-(3,4,5-tribromo-2-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester.
 3. The compound according to claim 1, alltrans-3,7-dimethyl-9-(3,4-dibromo-5-methyl-2-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester.
 4. The compound according to claim 1, alltrans-3,7-dimethyl-9-(2,4-dimethyl-5-chloro-3-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester.
 5. The compound according to claim 1, alltrans-3,7-dimethyl-9-(2,4-dimethyl-5-methoxy-3-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester.
 6. The compound according to claim 1, alltrans-3,7-dimethyl-9-(2,4-dichloro-5-methyl-3-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester.
 7. The compound according to claim 1,3,7-dimethyl-9-(2,4-dimethyl5-methoxymethyl-3-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester.
 8. The compound according to claim 1, alltrans-3,7-dimethyl-9-(2,4-dimethyl-5-dimethylamino-3-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester.
 9. The compound according to claim 1, alltrans-3,7-dimethyl-9-(2,5-dichloro-3-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester.
 10. The compound according to claim 1, alltrans-3,7-dimethyl-9-(2,4,5-trimethyl-3-thienyl)-2,4,6,8-nonatetraen-1-al.11. The compound according to claim 1,2,4,6-trans-8-cis-3,7-dimethyl-9-(3,4,5-tribromo-2-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester.
 12. The compound according to claim 1, alltrans-3,7-dimethyl-9-(3,4-dibromo-2-thienyl)-2,4,6,8-nonatetraenoic acidethyl ester.
 13. The compound according to claim 1,2,4,6-trans-8-cis-3,7-dimethyl-9-(3,4-dibromo-5-methyl-2-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester.
 14. The compound according to claim 1, alltrans-3,7-dimethyl-9-(2,4-diethoxycarbonyl-5-acetylamino-3-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester.
 15. The compound according to claim 1, alltrans-3,7-dimethyl-9-[2,4-dimethyl-5-(methylthio)-3-thienyl]-2,4,6,8-nonatetraenoicacid ethyl ester.
 16. The compound according to claim 1, alltrans-3,7-dimethyl-9-(2,5-dichloro-4-methyl-3-thienyl)-2,4,6,8-nonatetraenoicacid ethyl ester.
 17. The compound according to claim 1, alltrans-3,7-dimethyl-9-(2,4,5-trimethyl-3-thienyl)-2,4,6,8-nonatetraen-1-ol.18. The compound according to claim 1, alltrans-3,7-dimethyl-9-(2,4,5-trimethyl-3-thienyl)-1-methoxy-2,4,6,8-nonatetraene.19. The compound according to claim 1, alltrans-3,7-dimethyl-9-(5-bromo-2-thienyl)-2,4,6,8-nonatetraenoic acidethyl ester.